BIOLOGICAL AND PSYCHOSOCIAL CORRELATES OF ADULT GENDER VARIANT IDENTITIES: NEW FINDINGS

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1 I: Persoality ad Idividual Differeces, 49(3), doi: /j.paid The origial publicatio is available at This versio of the paper icludes additioal data that could ot be icluded i the prit versio due to word limit restrictios. BIOLOGICAL AND PSYCHOSOAL CORRELATES OF ADULT GENDER VARIANT IDENTITIES: NEW FINDINGS Jaimie F. Veale,.A. 1, Dave E. Clarke, Ph.D. School of Psychology, assey Uiversity, Albay Campus, New Zealad. Terri C. Lomax, Ph.D. Idepedet researcher, Welligto, New Zealad. ABSTRACT This study examied biological ad psychosocial variables that are relevat to the etiology of geder-variace. Data were collected over the iteret from 2277 participats of either geder who idetified as trassexual, other geder-variat, ad ot geder-variat. We foud umber of geder-variat relatives, hadedess, emotioal abuse, figer legth ratios (2D:4D), ad systematizig sigificatly predicted Adult Geder-Variace amog participats of both geders. Adult Geder-Variace was also predicted by umber of older brothers amog birth-assiged males. No sigificat differeces were foud i extreme righthadedess or metal rotatio. No sigificat iteractio effects were foud with sexual orietatio. While these fidigs are geerally cosistet with past research, there were limitatios of the iteret-based methodology, icludig a o-represetative sample. KEY WORDS: trassexualism; geder-variace; etiology; geder idetity; 2D:4D; abuse; systematizig; hadedess. INTRODUCTION A umber of studies have reported biological ad psychosocial correlates relevat to the etiology of geder-variace. However, oe of these studies assessed more tha a few of 1 To whom correspodece should be addressed at School of Psychology, assey Uiversity, Aucklad Campus, Private Bag , North Shore ail Cetre, Aucklad 0745, New Zealad; jfveale@yahoo.co.z

2 Jaimie Veale, Dave Clarke, ad Terri Lomax 2 these i oe study. Also, ofte these studies have ot bee replicated i the academic literature ad sometimes they do ot iclude compariso groups of o geder-variat (NGV) participats. Veale, Clarke, ad Lomax (2010b) reviewed previous studies of these correlates. They reported evidece for a geetic compoet of geder-variace based o studies of twis ad other withi-family cocordace ad of studies that have looked specifically at gees. They also reported evidece that preatal adroge levels correlate with geder-variace, from studies of figer legth ratios (2D:4D) of trassexuals, ad of idividuals with polycystic ovary sydrome ad itersex ad related coditios beig more likely to have a geder-variat idetity. Also, there is evidece that that trassexuals have some parts of their brai structure that is sex atypical, a greater likelihood of o-right-hadedess, a greater tedecy to report childhood abuse, ad male-to-female (F) trassexuals to have a greater umber of older brothers (Veale et al., 2010b). The etiological relevace of some of these variables is briefly explaied here. The ratio betwee the legth of the secod ad fourth figers (2D:4D) ad ability to metally rotate three-dimesioal objects are believed to be a idicator of preatal sex hormoe levels (see Veale et al., 2010b for a review). The causes of o-right hadedess are ot completely uderstood. There is evidece that o-right hadedess is associated with icreased preatal adroge levels ad developmetal istability. Developmetal istability refers to a persos susceptibility to developmetal disturbaces which result i reduced reproductive fitess ad icreased likelihood of impaired eurodevelopmet (Veale et al., 2010b). The elevated umber of older brothers foud i F trassexuals (e.g. Blachard, Zucker, Cohe-Ketteis, Goore, & Bailey, 1996) has also bee foud i NGV homosexual males. It has bee proposed each male fetus results i progressive immuisatio of Y chromosome liked atiges for the followig male fetus which results i less brai masculiisatio (Blachard & Bogaert, 1996). The aim of the preset study is to replicate the fidigs of previous research o umber of sibligs, withi family cocordace of geder-variace, hadedess, abuse, 2D:4D, ad metal rotatio ad explore the correlatio with systematizig ad paretal age ad cohabitatio amogst a large coveiece sample of geder-variat participats ad NGV comparisos. This is the first study to look at a comprehesive rage of these correlates ad to gai some idea of the relative stregth of each of them usig regressio aalysis. We hypothesize that, cosistet with previous research, there will be differeces betwee gedervariat participats ad compariso groups i the biological ad psychosocial variables.

3 Correlates of Geder-Variat Idetities 3 ETHOD Participats Participats were recruited for a iteret-based survey ivestigatig the developmet of geder ad sexuality through lesbia, gay, bisexual, ad trasgeder (LGBT) related olie forums ad mailig lists ad Google olie advertisig. A press release was also put out by assey Uiversity which attracted some o-lgbt participats. We received 2708 resposes to the questioaire; however, the data from 431 resposes could ot be icluded because they were duplicates or were ot complete eough to be icluded i this study. This left a coveiece sample of Participats were mostly Europea, well-educated ad livig i Wester coutries. Further data o ethicity, coutry, level of educatio, ad age are give by Veale, Clarke, ad Lomax (2009). ale assigmet at birth was reported by 66% of participats. 41% of birthassiged males ad 19% of birth-assiged females idetified as trassexual; 43% of birthassiged males ad 33% of birth-assiged females idetified as a other geder-variat idetity (OGV; trasvestite, geder queer, drag artist, cross-dresser, adrogyge, or bi-, third-, omi-, or o-gedered); ad 17% of birth-assiged males ad 48% of birth-assiged females did ot idetify as a geder-variat idetity (NGV). easures Two versios of this questioaire were completed. The first versio collected the first 681 resposes. The questioaire was upgraded to a secod versio which icluded additioal questios (outlied below) for the remaiig 1596 resposes. Proportio of gay/geder variat relatives Participats were asked about the umbers of sibligs, auts, ad ucles they had, ad whether these relatives (as well as parets ad gradparets) are/were homosexual/bisexual, trassexual, or OGV. This umber was coverted ito a proportio of relatives with parets ad sibligs receivig twice the weightig as gradparets, auts, ad ucles because they have twice the geetic cocordace. Participats who completed the secod versio of the questioaire were also asked their parets age at the time of their birth. Abuse Emotioal abuse was measured usig the five-item emotioal abuse subscale of the Childhood Trauma Questioaire Short Form (Berstei et al., 2003). I the preset study, this scale had a iteral cosistecy coefficiet of α =.84. Each item begis with the phrase

4 Jaimie Veale, Dave Clarke, ad Terri Lomax 4 Whe I was growig up, ad participats select from a 7-poit Likert respose scale from Not true at all to Very true. Berstei et al. reported a iteral cosistecy coefficiet of α =.87 amog a ormative sample of 579 America adults. They also reported evidece for criterio-related validity with a correlatio of.48 betwee the scale ad therapist observatios of emotioal abuse amog a sample of adolescet ipatiets. Cofirmatory factor aalyses have supported the costruct validity of the emotioal abuse subscale amog adolescet psychiatric ipatiets, adult substace abusers, ad female health maiteace orgaizatio members (Berstei, Ahluvalia, Pogge, & Hadelsma, 1997; Berstei et al., 1994; Berstei et al., 2003). Physical abuse was measured usig oe item of the Child Abuse ad Trauma Scale that has bee show to be a accurate screeer for physical abuse (Thombs, Berstei, Ziegelstei, Beett, & Walker, 2007). Sexual abuse was measured usig a sigle questio desiged by the third author (Veale, Clarke, & Lomax, 2010a). This questio assessed both the participats certaity ad severity of the abuse. Hadedess ad 2D:4D Hadedess was assessed usig the Ediburgh Hadedess Ivetory (Oldfield, 1971) usig the respose scales suggested by Bogaert (2007): : 5-poit resposes from Always right to Always left. Categorizatio of participats hadedess also followed Bogaert, with scores of 100 categorized as extreme-right-haded, scores from 50 to 95 moderate-righthaded ad scores from -100 to 45 o-right haded. Legths of participats secod ad fourth figers o the right had were also collected. The specific istructios give to participats were take from the BBC Iteret Study (Reimers, 2007). Participats were also give the optio of usig a olie ruler which is simply the image of a ruler i a pop-up browser widow (see Veale, 2008, details from the author, for a assessmet of the olie ruler). Sexual orietatio This was measured usig participats self-ratig o six-item Kisey scales for sexual fatasies ad experiece used by Bailey (1989). Participats were categorized as homosexual (relative to birth-assiged sex) if they reported Kisey scores of 5 or 6 for both fatasies ad experiece. 77 (31%) of male NGV participats who respoded to this questio were classified as homosexual. Correspodig umbers for birth-assiged male OGV participats

5 Correlates of Geder-Variat Idetities 5 were 50 (8%), F trassexuals 48 (8%), female NGV 31 (8%), birth-assiged female OGV 30 (12%), ad F trassexuals 18 (12%). etal rotatio ad systematizig Spatial ability was measured usig the etal Rotatio Test (adapted from Vadeberg & Kuse, 1978). I this 30-item test, participats were required to view two threedimesioal cuboids, ad decide whether they are the same (oly rotated) or differet objects. Participats were give two miutes to give as may correct aswers as possible ad were pealized for icorrect resposes. This test has cosistetly outperformed other measures i differetiatig sex ad sexual orietatio, ad is thought to measure uderlyig eurocogitive structural differeces (see Rahma & Wilso, 2003 for a review). Systematizig was measured oly i the secod versio of the questioaire usig 8 items take from the Systematizig Quotiet Short Form (Wakabayashi et al., 2005). This scale measures desire to costruct ad aalyze systems. Participats respod to statemets (e.g., I fid it easy to grasp exactly how odds work i bettig. ) o a 7-poit Likert scale from Strogly agree to Strogly disagree. Wakabayashi et al. reported a iteral cosistecy coefficiet of.88, factorial validity, ad discrimiat validity betwee males versus females, sciece studets versus humaities studets amog a 23-item versio of the Systematizig Quotiet. I the preset study, this scale had a iteral cosistecy coefficiet of α =.74. Social desirability The Balaced Ivetory of Desirable Respodig (BIDR) short form (Stober, Dette, & usch, 2002) was icluded to measure social desirability. This 16-item scale used 7-poit Likert scales from Not true at all to Very true. Stober et al. reported iteral cosistecies of.66 for Self Deceptio ad.67 for Impressio aagemet. I the preset study, the correspodig iteral cosistecies were.70 ad.60. A umber of studies have reported evidece for cocurret validity with the BIDR correlatig highly with other measures of social desirability (Layo & Carle, 2007; Paulhus, 1988; Stober et al., 2002). Adult Geder Variace Adult Geder-Variace was measured usig the four items o the Cross-Geder Idetity, Cross-Geder Femiizatio, ad Cross-Geder Social/Sexual Role subscales of Docter ad Flemig s (1992) Cross Geder Questioaire that were appropriate for NGV participats ad for birth-assiged females if the geders i the questios were reversed (e.g. Sice the age of 17, have you wished you had bee bor a boy istead of a girl? was

6 Jaimie Veale, Dave Clarke, ad Terri Lomax 6 reversed to Sice the age of 17, have you wished you had bee bor a girl istead of a boy? ). Participats respoded o 7-poit Likert scales from Strogly agree to Strogly disagree. From a sample of 682 birth-assiged male trasvestites ad trassexuals, Docter ad Flemig reported iteral cosistecy coefficiets of o the four subscales of the Cross Geder Questioaire, ad the scale showed discrimiat validity betwee trasvestite ad trassexual groups. This scale icluded a additioal four items askig participats how masculie/femiie they thik they are ad how masculie/femiie they exhibit themselves to others. I the preset study, the Adult Geder-Variace scale had a iteral cosistecy coefficiet of α =.85. This scale was able to sigificatly distiguish betwee the three levels of geder-variat idetity with large effect sizes (partial η 2 of.44 i birth-assiged males ad.48 i birth-assiged females), suggestig costruct validity. Procedure This survey was hosted olie, ad participats were recruited through Iteret advertisig ad from the first author cotactig various iteratioal gay, lesbia, bisexual, or trasgeder-related groups. Data aalysis was coducted usig SPSS versio 15. Approval for this research was grated by assey Uiversity Huma Ethics committee. Results Betwee group differeces Biological ad psychosocial variables were subjected to two-way aalysis of variace havig three levels of geder-variat idetity (trassexual, OGV, NGV) ad two levels of birth-assiged geder (male, female). Results of these ANOVAs are preseted i Table 1. Sigificat differeces betwee geder idetity groups i Table 1 are outlied here. Female-assiged OGVs reported a sigificatly greater proportio of gay relatives tha all of the other groups except F trassexuals; trassexuals ad OGVs reported a sigificatly greater umber of geder-variat relatives, a greater amout of emotioal, physical, ad sexual abuse, ad scored sigificatly lower o the Ediburgh Hadedess Ivetory (suggestig a tedecy towards o-right-hadedess) tha NGVs; OGVs scored sigificatly lower tha NGVs o etal Rotatio; F trassexuals ad female NGVs scored sigificatly lower tha F trassexuals ad male NGVs o the Systematizig Quotiet; F trassexuals had a sigificatly older mother's age at birth tha F trassexuals; ad trassexuals had sigificatly fewer years livig with both parets ad with

7 Correlates of Geder-Variat Idetities 7 Table 1 Two-way ANOVAs of biological ad psychosocial variables with level of gedervariat idetity ad birth-assiged geder as idepedet variables. Proportio of gay relatives Proportio of geder- F variat F relatives ess Ivetory Ediburgh Haded- Emotioal abuse Physical abuse F F Trassexual OGV NGV F geder F idetity F iteractio , p <.01; 53.88, 3.86, p =.02; 2.25, 4.32, p =.01; 3.22, p <.01 p >.05 p = , 14.56, 0.23, p >.05; p <.01; p >.05; 4.04, 20.27, 0.32, p =.05 p <.01 p > , 12.57, 0.63, p >.05 p <.01 p > , 22.71, 2.03, p <.01 p <.01 p > , 13.75, 2.19, p >.05 p <.01 p >.05

8 Jaimie Veale, Dave Clarke, ad Terri Lomax 8 F Sexual , 5.91, 1.10, abuse p <.01 p <.01 p >.05 F D:4D , 2.73, 2.98, p >.05 p >.05 p = F etal , 4.94, 2.07, rotatio p >.05 p =.01 p >.05 F System , 0.84, 33.33, atizig quotiet p >.05 p >.05 p <.01 F other s , 0.35, 4.10, age at partici p <.01 p >.05 p =.02 pat s F birth

9 Correlates of Geder-Variat Idetities 9 Father s age at partici- pat s birth Years util age 18 livig F with both F parets Years util age 18 livig with F mother Years util age 18 livig with F father , p = , p =.02; 7.49, 0.84, p > , p <.01; 3.66, 2.26, p > , p >.05; 1.38, p =.01 p =.03 p > , p >.05; 3.57, 1.27, p >.05; 0.84, 0.61, p >.05; 0.49, p >.05 p >.05 p > , p =.01; 8.62, 5.44, p <.01; 3.19, 2.52, p >.05; 1.35, p <.01 p =.04 p >.05 Note: = birth-assiged male; F = birth-assiged female; OGV = other geder-variat idetity; NGV = o geder-variat idetity; = 95% cofidece iterval; depedet variable ot ormally distributed secod F scores for rak-order tests. their father util age 18 tha the other two groups. The ANOVA for metal rotatio scores did ot chage sigificatly whe age ad level of educatio were added as covariates. A omial regressio was calculated to see if the proportio of extreme- ad oright haded participats differed amog birth-assiged geder, ad geder-variat idetity. NGV participats were less likely to be o-right-haded, Wald χ²(1, = 1491) = 26.18, p <

10 Jaimie Veale, Dave Clarke, ad Terri Lomax 10.01, odds ratio =.40, ad more likely to be extreme-right-haded tha trassexuals, Wald χ²(1, = 1491) = 6.16, p =.01, odds ratio = OGV participats were less likely to be o-right-haded tha trassexuals, Wald χ²(1, = 1491) = 8.66, p <.01, odds ratio =.66. Sexuality as a moderatig variable Whe homosexuality relative to birth-assiged sex (two levels homosexual, ohomosexual) was added as a predictor variable to make three-way ANOVAs, there were o sigificat mai effects for homosexuality o ay of the variables i Table 1. Hadedess as a moderatig variable O separate tests, hadedess (two levels right-haded, o-right-haded) was added as a predictor variable to make three-way ANOVAs. For proportio of geder-variat relatives, F(1, 2066) = 9.17, p <.01, emotioal abuse, F(1, 1833) = 9.60, p <.01, ad metal rotatio, F(1, 1294) = 6.48, p =.01, there were a sigificat mai effects for hadedess. No-right-haded participats reported sigificatly more geder-variat relatives ad emotioal abuse ad scored lower o metal rotatio tha right-haded participats. Liear Regressio Liear regressio models for predictors of Adult Geder-Variace amog birthassiged males ad females are outlied i Tables 2 ad 3 respectively. I these aalyses 2D:4D ad proportio of geder-variat relatives were cetered the mea subtracted from each score to elimiate colliearity with the itercept. Predictor variables were oly icluded if doig so resulted i a improvemet of adjusted r². Two comparative models for are outlied i Tables 2 ad 3 the secod model icludes the Systematizig Quotiet. This was give its ow model because it is questioable whether it is measurig a biological marker (a male brai ) which could cause a geder-variat idetity. Amog the predictors of these models there was o evidece of multicolliearity - the greatest variace iflatio factor score was 1.11, the lowest tolerace score was.90, ad the highest coditio idex score was Sigificat predictors amogst both birth-assiged geders were geder-variat relatives, hadedess, emotioal abuse, 2D:4D, ad systematizig. Number of older brothers predicted Adult Geder-Variace i oly birth-assiged males. Social desirability No sigificat correlatio was foud betwee BIDR ad reported 2D:4D amog geder-variat (trassexual ad OGV) participats of both birth-assiged sexes. There was also o sigificat correlatio betwee geder-variat birth-assiged females BIDR ad the

11 Correlates of Geder-Variat Idetities 11 Systematizig Quotiet (r =.12). While the correspodig correlatio amog birth-assiged males was margially sigificat (r =.08, p =.05), this was ot i the directio of appearig more atypical of birth-assiged geder. Table 2 Liear regressio for biological ad psychosocial variables predictig Adult Geder- Variace amog birth-assiged males. Predictor odel 1 odel 2 β t p β t p Number of older brothers (raked) Proportio of geder-variat relatives (raked) Ediburgh Hadedess Scale Emotioal abuse < <.01 2D:4D < Systematizig Quotiet <.01 Itercept (ustadardized beta) < <.01 r² Adjusted r² Note: = 667, β = stadardized regressio weights, 1 higher scores for right-hadedess Table 3 Liear regressio for biological ad psychosocial variables predictig Adult Geder- Variace amog birth-assiged females. Predictor odel 1 odel 2 β t p β t p Proportio of geder-variat relatives (raked) Ediburgh Hadedess Scale < Emotioal abuse < D:4D other s age at participat s birth Systematizig Quotiet <.01 Itercept (ustadardized beta) < r² Adjusted r² Note: = 298, β = stadardized regressio weights

12 Jaimie Veale, Dave Clarke, ad Terri Lomax 12 Sexual orietatio correlatios Table 4 shows there was o relatioship betwee sexual orietatio ad most of the biological ad psychosocial correlates that predicted adult geder-variace o the regressio models. Also, birth-assiged males did ot have differig correlatio coefficiets to birthassiged females. Cofidece itervals were calculated usig Fisher r-to-z trasformatios. Table 4 Correlatio betwee sexual orietatio Kisey score ad variables predictig adult geder-variace. Sexual fatasy Sexual experiece BA ale BA Female BA ale BA Female Older brothers (raked) r 95%.10**.04 to to to to.13 Proportio of gedervariat relatives (raked) r 95% to to * -.13 to to.08 Ediburgh hadedess r 95% to to to.07.10*.01 to.20 Emotioal abuse r D:4D r other s age r Systematizig r 95% -.16** -.23 to to ** -.18 to to.06 Note: * p <.05 ** p <.01; BA = birth-assiged; = 95% cofidece iterval Withi family cocordace of trassexualism Because a very small proportio of participats reported trassexual relatives this variable was ot icluded i the statistical aalyses. However, there were six F trassexuals who reported a trassexual relative two brothers, a father, a materal ucle, a pateral aut, ad a materal gradparet. Two F trassexuals reported a trassexual relative a brother ad a materal aut. Assumig that participats were aware of the geder idetity of all their reported relatives, this equates to a prevalece ratio of trassexualism of 1:1479 amog relatives of F trassexuals ad 1:969 amog relatives of F trassexuals.

13 Correlates of Geder-Variat Idetities 13 Discussio A umber of biological ad psychosocial variables were foud to be associated with Adult Geder-Variace. I the variables that showed betwee-group differeces, OGV participats teded to score itermediate betwee trassexuals ad NGVs. This is cosistet with a dosage effect. Those with the more extreme dose of the biological or psychosocial variable are more likely to develop a more extreme geder-variat idetity. This is also supportive of the hypothesis that OGV idetities are less extreme maifestatios trassexualism, rather tha distict occurreces (cf. Veale, Lomax, & Clarke, i press). Each of the variables assessed i this research are discussed i tur. Number of sibligs Although there were o sigificat betwee group differeces i umber of sibligs, umber of older brothers was a sigificat predictor i the regressio model amog birthassiged males. This fidig is cosistet with past research (reviewed by Veale et al., 2010b). However, i cotrast to previous fidigs, this effect did ot appear to be related to sexual orietatio typology. I lie with past research, there were o sigificat betweegroup differeces for umber of older sisters ad umber of youger brothers or sisters ad oe of these variables were sigificat predictors i the regressio model. Withi family cocordace of sexuality ad geder variat relatives Birth-assiged female participats i this research were sigificatly more likely to report homosexual/bisexual relatives ad amog these, geder-variat birth-assiged females were especially likely to report such relatives. There was o tedecy for birth-assiged females to be more likely tha birth-assiged males to be homosexual/bisexual (relative to birth-assiged sex) i this study, meaig this effect could ot be explaied by the icreased reportig withi-family cocordace of homosexuality amog relatives of homosexual birthassiged females (Bailey & Beishay, 1993; Bailey et al., 1999). Trassexuals ad OGVs of both geders were sigificatly more likely to report geder-variat relatives tha NGVs. This is cosistet with previous research that has foud elevated levels of withi-family cocordace of geder-variace (reviewed by Veale et al., 2010b). Give the methodology of this research, it is ot possible to distiguish whether this is the result of a geetic or social learig effect. However, it has bee reported elsewhere that usually these idividuals are ot aware that their relative is geder-variat util they reach adulthood (Gree, 2000), suggestig a geetic explaatio is more likely. The gees

14 Jaimie Veale, Dave Clarke, ad Terri Lomax 14 that play a role i this developmet may be those that are resposible for preatal adroge levels. However, the operatioal defiitio of geder-variat relatives was somewhat ope to iterpretatio. Participats were asked the umber of relatives they kow or suspect are geder-variat (e.g. trassexuals, trasgeder, trasvestites, cross-dressers, drag artistes, geder-queer). It is possible that geder-variat participats had a lower threshold for describig their relatives as geder-variat tha NGV participats did. O the other had, it might be expected that NGV participats would report a greater umber of geder-variat relatives as oe of the reasos that they had become iterested i our research i the first place could have bee because of havig a geder-variat relative. For this reaso we did ot actively recruit participats from olie groups for sigificat others of geder-variat persos. The operatioal defiitio for trassexual relatives was stricter a participat eeded to kow this relative was trassexual. Cosistet with the fidigs of geder-variat relatives, the prevalece of trassexualism amogst the relatives of trassexuals was higher tha the most liberal estimates amogst the geeral populatio (Tsoi, 1988; Veale, 2008). Hadedess This study foud o-right-hadedess was sigificatly related to Adult Geder- Variace i both the betwee-group ad regressio aalyses amog participats assiged to either geder. This result is i lie with previous fidigs (reviewed by Veale et al., 2010b) ad cosistet with the hypothesis that developmetal istability has a role to play i the developmet of geder-variace. However, i cotrast to the fidigs of Herma-Jegliska, Dulko, ad Grabowska (1997), this study did ot fid a elevated level of extreme-righthadedess amog geder-variat participats, which is usupportive of the developmetal istability hypothesis. Abuse This study foud icreased levels of emotioal, physical, ad sexual abuse amog trassexuals ad OGVs. This is i lie with treds of previous research (reviewed by Veale et al., 2010b) ad this is oe of the few studies to use a compariso group. Emotioal abuse was the oly sigificat abuse predictor of Adult Geder-Variace i the regressio models. This is likely to be because emotioal abuse was the strogest predictor ad ay additioal predictio from physical ad sexual abuse was ot sigificat. Usig structural equatio

15 Correlates of Geder-Variat Idetities 15 modelig, (Veale et al., 2010a) foud evidece that abuse was a cause of geder-variace amog birth-assiged males ad a effect of geder-variace amog birth-assiged females. The sexual abuse fidigs should also be iterpreted i light of the fact that it was measured usig a questio i which psychometric properties are ot available for. This questio was also double-barreled assessig both severity ad certaity which is a suboptimal way to costruct items. 2D:4D No betwee-group differeces were foud i 2D:4D. However, 2D:4D was a sigificat predictor i the regressio models for both birth-assiged geders i the expected directios masculiized 2D:4D predicted geder-variace i birth-assiged females ad femiized 2D:4D predicted geder-variace i birth-assiged females. Geerally this is cosistet with previous research (reviewed by Veale et al., 2010b) ad supportive of the preatal hormoe hypothesis. This research did ot fid the usual sex differece betwee NGV males ad female. This is likely to be because (1) a sigificat proportio NGV participats i this research were ot heterosexual ad o-heterosexuality has bee related to sex-atypical 2D:4D (e.g. aig, Churchill, & Peters, 2007) ad (2) 2D:4D was self-measured which has bee show to result i icreased measuremet error (aig et al., 2007). etal rotatio No sigificat relatio betwee metal rotatio score ad geder-variace was foud o ay of the statistical tests so o further evidece for the eurobiological explaatio of geder-variace ca be take from these data. However, the metal rotatio test we used differed from the origial by Vadeberg ad Kuse (1978) i that we oly had oe compariso stimulus istead of three 1 ; it is likely that this made the test less difficult. Also, this test did ot show the usual sex differece amog NGV participats. Agai, this could have bee because a sigificat proportio NGV participats were ot heterosexual, ad oheterosexuality has bee related to sex-atypical metal rotatio scores (Peters, aig, & Reimers, 2007). 1 This alteratio was made because we were ot able to publish the origial test olie for copyright reasos.

16 Jaimie Veale, Dave Clarke, ad Terri Lomax 16 Systematizig Quotiet The cocept of systematizig was has bee used as a explaatio of the developmet of autism (Baro-Cohe, 2002). Systematizig refers to a perso s propesity to uderstad ad be able to costruct systems. Examples of systems iclude computers, musical istrumets, weather, mathematics, political systems, ad library orgaizig systems (Baro- Cohe, 2002). The Systematizig Quotiet was developed to measure this costruct. Other studies (as well as this oe) have show that NGV males score sigificatly higher o this measure tha NGV females (Wakabayashi et al., 2007). Baro-Cohe proposed a theory called the extreme male brai theory of autism postulatig that persos with autism have a markedly greater systematizig ability (a male-ehaced trait) tha their empathizig ability (a female-ehaced trait) ad as the ame of the theory suggests, those scorig higher o systematizig have more of a male brai. Whilst social eviromet may play a role i systematizig developmet, there is evidece that autism develops preatally, probably due to the effects of preatal hormoe levels (reviewed i Baro-Cohe, Kickmeyer, & Belmote, 2005). A recet study of childre also foud that systematizig was sigificatly predicted by fetal testosteroe levels measured i amiotic fluid i fact it was a stroger predictor of this tha sex itself (Auyeug et al., 2006). Therefore, there is reaso to believe that preatal adroge levels are a sigificat cotributor to the developmet of systematizig. The Systematizig Quotiet was icluded as a exploratory variable as this is the first time we are aware that this variable has bee used as a proxy measure of preatal adroge exposure. As expected, we foud that systematizig was a sigificat predictor of Adult Geder-Variace i both the betwee-group ad regressio aalyses amog participats assiged to both geders at birth. Systematizig was a especially strog predictor amog birth-assiged males, where its iclusio doubled the variace that was accouted for i the regressio model. This fidig is also supportive of the eurobiological basis as a explaatio of geder-variace. The fidig of o sigificat correlatio betwee BIDR ad systematizig i the expected directio suggests that geder-variat participats were ot distortig their systematizig resposes to appear more atypical of birth-assiged geder. It should, however, be oted that the factors resposible for developmet of systematizig are still ot well uderstood. It would be expected that geder-variat childre would pursue play ad

17 Correlates of Geder-Variat Idetities 17 educatioal activities that would impact o the developmet of their systematizig ad empathizig amogst geder-variat populatios. Paretal age While it is uclear whether this would play a role as a biological or psychosocial factor, there is evidece that male homosexuality is related to higher materal age (Frisch & Hviid, 2006; Hare & ora, 1979), so this variable was explored i this study. While there was o evidece that paretal age was associated with Adult Geder-Variace amog birthassiged males, amog birth-assiged females, materal age was a margially sigificat predictor of Adult Geder-Variace. Give the margial ature of the fidig, replicatio is eeded before speculatig o the role this plays i geder-variace developmet. Sexual orietatio as a moderatig variable Whe sexual orietatio typology was added to the betwee-group aalysis it did ot produce ay mai or iteractio effects with degree of geder-variat idetity. This is despite the fact that previous researchers have proposed distict etiologies for F trassexuals depedet o sexual orietatio type (Bailey & Triea, 2007; Freud & Blachard, 1993; Freud, Steier, & Cha, 1982). Closer ispectio of the correlatio betwee sexual orietatio ad the variables that predicted Adult Geder-Variace i the liear regressio models foud that most were ot sigificatly related to sexual orietatio. Also, oe of the correlatio coefficiets differed sigificatly betwee birth-assiged males ad females as might be expected if the etiology of geder-variace amog birth-assiged males but ot birth-assiged females could be differetiated by sexual orietatio. Lawrece ad Bailey (2009) cocluded that F trassexual participats i our previous research that used similar iteret methodology (Veale, Clarke, & Lomax, 2008) were overwhelmigly of the o-adrophilic subtype. Although a small but sigificat proportio of our birth-assiged male geder-variat participats reported they were exclusively adrophilic o both sexual fatasy ad experiece, our fidigs should be replicated o a o-iteret sample for verificatio. Hadedess as a moderatig variable No-right-haded participats reported sigificatly more geder-variat relatives ad emotioal abuse ad scored lower o metal rotatio tha right-haded participats. The meaig of these fidigs is uclear ad replicatio is eeded before ay

18 Jaimie Veale, Dave Clarke, ad Terri Lomax 18 Limitatios ad coclusios The aim of the study is ot to assess biological versus psychosocial iflueces. We could ot come to ay realistic coclusios about this because we have oly bee able to predict such a small amout of the variace i the regressio models. There is a lot of ifluece o Adult Geder-Variace that is ot accouted for i this model due to 1) measuremet error ad 2) iflueces that we have ot bee able to measure. (For a assessmet of the relative stregth of biological versus psychosocial iflueces, see Veale, Clarke, & Lomax, 2010c.) A sigificat limitatio of this research was the respose rate 25% of participats who bega the questioaire did ot complete all the questios. Also, because some of the variables were icluded i the questioaire later i the research collectio process the data were ot missig at radom, so listwise deletio was required for the regressio aalyses. This resulted i oly 42% of the participats that that started the questioaire beig able to be icluded i these aalyses. Secodly, it should be oted that this study did ot fid the usual sex differeces betwee NGV participats i 2D:4D or etal Rotatio. It is therefore difficult to draw strog coclusios about the associatio of these variables with geder-variace i our study. Fially, because all of the recruitmet ad data collectio was carried out olie, this research oly represeted those from the wider populatio who egaged with the Iteret. However, with some exceptios, the fidigs seem to be i lie with those of previous research usig cliical samples. Future research is required to replicate these fidigs amog a o-iteret-based sample. REFERENCES Auyeug, B., Baro-Cohe, S., Chapma, E., Kickmeyer, R., Taylor, K., & Hackett, G. (2006). Foetal testosteroe ad the child systemizig quotiet. Europea Joural of Edocriology, 155, Bailey, J.. (1989). A test of the materal stress hypothesis for huma male homosexuality (Doctoral dissertatio, Uiversity of Texas at Austi). Dissertatio Abstracts Iteratioal, 50(10), 4761B. Bailey, J.., & Beishay, D. S. (1993). Familial aggregatio of female sexual orietatio. America Joural of Psychiatry, 150,

19 Correlates of Geder-Variat Idetities 19 Bailey, J.., Pillard, R. C., Dawood, K., iller,. B., Farrer, L. A., Trivedi, S., et al. (1999). A family history study of male sexual orietatio usig three idepedet samples. Behavior Geetics, 29, Bailey, J.., & Triea, K. (2007). What may trasgeder activists do't wat you to kow ad why you should kow it ayway. Perspectives i Biology ad edicie, 50, Baro-Cohe, S. (2002). The extreme male brai theory of autism. Treds i Cogitive Scieces, 6, Baro-Cohe, S., Kickmeyer, R. C., & Belmote,. K. (2005). Sex differeces i the brai: Implicatios for explaiig autism. Sciece, 310, Berstei, D. P., Ahluvalia, T., Pogge, D., & Hadelsma, L. (1997). Validity of the Childhood Trauma Questioaire i a adolescet psychiatric populatio. Joural of the America Academy of Child ad Adolescet Psychiatry, 36, Berstei, D. P., Fik, L., Hadelsma, L., Foote, J., Lovejoy,., Wezel, K., et al. (1994). Iitial reliability ad validity of a ew retrospective measure of child abuse ad eglect. America Joural of Psychiatry, 151, Berstei, D. P., Stei, J. A., Newcomb,. D., Walker, E., Pogge, D., Ahluvalia, T., et al. (2003). Developmet ad validatio of a brief screeig versio of the Childhood Trauma Questioaire. Child Abuse ad Neglect, 27, Blachard, R., & Bogaert, A. F. (1996). Homosexuality i me ad umber of older brothers. America Joural of Psychiatry, 153, Blachard, R., Zucker, K. J., Cohe-Ketteis, P. T., Goore, L. J. G., & Bailey, J.. (1996). Birth order ad siblig sex ratio i two samples of Dutch geder-dysphoric homosexual males. Archives of Sexual Behavior, 25, Bogaert, A. F. (2007). Extreme right-hadedess, older brothers, ad sexual orietatio i me. Neuropsychology, 21, Docter, R. F., & Flemig, J. S. (1992). Dimesios of trasvestism ad trassexualism: The validatio ad factorial structure of the Cross-Geder Questioaire. Joural of Psychology ad Huma Sexuality, 5, Freud, K., & Blachard, R. (1993). Erotic target locatio errors i male geder dysphorics, paedophiles, ad fetishists. British Joural of Psychiatry, 162, Freud, K., Steier, B. W., & Cha, S. (1982). Two types of cross-geder idetity. Archives of Sexual Behavior, 11,

20 Jaimie Veale, Dave Clarke, ad Terri Lomax 20 Frisch,., & Hviid, A. (2006). Childhood family correlates of heterosexual ad homosexual marriages: A atioal cohort study of two millio Daes. Archives of Sexual Behavior, 35, Gree, R. (2000). Family coocurrece of "geder dysphoria": Te sibligs or paret-child pairs. Archives of Sexual Behavior, 29, Hare, E. H., & ora, P. A. (1979). Paretal age ad birth order i homosexual patiets: A replicatio of Slater's study. British Joural of Psychiatry, 134, Herma-Jegliska, A., Dulko, S., & Grabowska, A.. (1997). Trassexuality ad adextrality: Do they share a commo origi? I L. Ellis & L. Ebertz (Eds.), Sexual orietatio: Toward a biological uderstadig. Westport, CT: Praeger. Layo, R. I., & Carle, A. C. (2007). Iteral ad exteral validity of scores o the Balaced Ivetory of Desirable Respodig ad the Paulhus Deceptio Scales. Educatioal ad Psychological easuremet, 67, Lawrece, A. A., & Bailey, J.. (2009). Trassexual groups i Veale et al. (2008) are "autogyephilic" ad "eve more autogyephilic" [Letter to the editor]. Archives of Sexual Behavior, 38, aig, J. T., Churchill, A. J. G., & Peters,. (2007). The effects of sex, ethicity, ad sexual orietatio o self-measured digit ratio (2D:4D). Archives of Sexual Behavior, 36, Oldfield, R. C. (1971). The assessmet ad aalysis of hadedess: The Ediburgh ivetory. Neuropsychologia, 9, Paulhus, D. L. (1988). Assessig self-deceptio ad impressio maagemet i self-reports: The Balaced Ivetory of Desirable Respodig. Upublished maual, Uiversity of British Columbia, Vacouver, Caada. Peters,., aig, J. T., & Reimers, S. (2007). The effects of sex, sexual orietatio, ad digit ratio (2D: 4D) o metal rotatio performace. Archives of Sexual Behavior, 36, Rahma, Q., & Wilso, G. D. (2003). Bor gay? The psychobiology of huma sexual orietatio. Persoality ad Idividual Differeces, 34, Reimers, S. (2007). The BBC Iteret Study: Geeral methodology. Archives of Sexual Behavior, 36, Stober, J., Dette, D. E., & usch, J. (2002). Comparig cotiuous ad dichotomous scorig of the Balaced Ivetory of Desirable Respodig. Joural of Persoality Assessmet, 78,

21 Correlates of Geder-Variat Idetities 21 Thombs, B. D., Berstei, D. P., Ziegelstei, R. C., Beett, W., & Walker, E. A. (2007). A brief two-item screeer for detectig a history of physical or sexual abuse i childhood. Geeral Hospital Psychiatry, 29, Tsoi, W. F. (1988). The prevalece of trassexualism i Sigapore. Acta Psychiatrica Scadiavica, 78, Vadeberg, S. G., & Kuse, A. R. (1978). etal rotatios, a group test of three-dimesioal spatial visualizatio. Perceptual ad otor Skills, 47, Veale, J. F. (2008). The prevalece of trassexualism amog New Zealad passport holders. Australia ad New Zealad Joural of Psychiatry, 42, Veale, J. F., Clarke, D. E., & Lomax, T. C. (2008). Sexuality of male-to-female trassexuals. Archives of Sexual Behavior, 36, Veale, J. F., Clarke, D. E., & Lomax, T. C. (2009). Appraisal of the idetity-defece model of geder-variace developmet ad compariso with Blachard's alterative. auscript submitted for publicatio. Veale, J. F., Clarke, D. E., & Lomax, T. C. (2010a). Abuse experieces amog persos with geder-variat idetities: cause or effect? auscript i preparatio. Veale, J. F., Clarke, D. E., & Lomax, T. C. (2010b). Biological ad psychosocial correlates of adult geder-variat idetities: A review. Persoality ad Idividual Differeces, 48, Veale, J. F., Clarke, D. E., & Lomax, T. C. (2010c). The relative ifluece of assiged geder ad preatal adroge exposure o geder idetity i itersex ad related coditios. auscript submitted for publicatio. Veale, J. F., Lomax, T. C., & Clarke, D. E. (i press). The idetity-defece model of gedervariace developmet. Iteratioal Joural of Trasgederism. Wakabayashi, A., Baro-Cohe, S., Uchiyama, T., Yoshida, Y., Kuroda,., & Wheelwright, S. (2007). Empathizig ad systemizig i adults with ad without autism spectrum coditios: Cross-cultural stability. Joural of Autism ad Developmetal Disorders, 37, Wakabayashi, A., Simo, B. C., Wheelwright, S., Goldefeld, N., Delaey, J., Fie, D., et al. (2005). The short forms of the Empathy Quotiet (EQ-short) ad the Systemizig Quotiet (SQ-short). Upublished mauscript.