Suggestions for future research

This thesis found evidence for a number of biological and psychosocial variables related to the development of gender identities. Future research could conduct

investigation into the relative importance of these predictor variables using dominance analysis (Budescu, 1993). Commonality analysis could be conducted to assess the amount of adult gender-variance that is explained by each predictor uniquely or common to a number of predictors (Seibold & McPhee, 1979). This analysis could further our understanding of whether there are different etiological pathways to gender- variant and gender-typical identity development as has been proposed.

Section 3.1.2.1 reviews follow-up of people who have intersex and related conditions with male-typical biology who were assigned female at birth. Many of these people were reported to have a female gender identity in adulthood. This suggests environmental encouragement of gendered behaviour plays a role as a psychosocial factor in gender identity development. This factor was overlooked in the present study. Future research could assess this.

As outlined in Section 9.2, this research was conducted on an internet-based sample that was susceptible to sampling bias. Future research could replicate these findings among a population-based sample by using a wider range of data collection methods.

This research examined one area related to gender identity development—the ways in which biological and psychosocial factors predict adult gender-variant identity.

Future research could look at broader areas. Blanchard’s theory proposed that cross- gender eroticism causes a gender-variant identity to develop in birth-assigned males with sexual attractions to females (Blanchard, 1991; Freund & Blanchard, 1993). This theory states that cross-gender eroticism is caused by an erotic target localisation error, but Blanchard never speculated what might cause this error. Boyd (2003) proposed that this error could occur because of being sexually intimidated by women in adolescence. A pathway for Blanchard’s theory that could be tested would look like: sexual

intimidation from women → cross-gender eroticism → adult gender-variance. It may be that the biological and psychosocial factors linked to gender-variant identity interact with other unknown factors to determine eventual gender identity and sexual attraction outcomes. A more recently developed theory proposes that

environmental tolerance or acceptance of early gender-variance expression, childhood coping and defence styles, and childhood personality all predict whether an individual with a gender-variant identity will repress that identity and develop along the non- androphilic pathway, or not and develop along the androphilic pathway (Veale et al., 2010). Some previous studies have assessed perceived environmental tolerance or acceptance of early gender-variance expression (B. Bullough & Bullough, 1997a; Langstrom & Zucker, 2005; Rieger et al., 2008) but these have not examined whether it is related to a androphilic/non-androphilic gender-variance experience. Also, no

previous research has assessed defence mechanisms and coping styles among persons with gender-variant identities. There is, however, some work on personality conducted on persons with gender-variant identities. In accordance with the theory, this work has found that those reporting a non-androphilic experience report less extraversion than those with a androphilic experience (Bentler & Prince, 1969; Smith, van Goozen, Kuiper, & Cohen-Kettenis, 2005a; Wilson & Gosselin, 1980). One study reported signs of agreeableness among participants with a non-androphilic experience (B. Bullough & Bullough, 1997b) in persons with gender-variant identities. Future research could assess the extent to which environmental tolerance or acceptance of early gender-variance expression, childhood coping and defence styles, and childhood personality predict whether an individual with a gender-variant identity will report an androphilic or non- androphilic gender-variance experience.

9.6Conclusions

This thesis broadened our understanding of etiological factors that are involved in gender-variant or gender-typical identity development. As with previous research, the current study provided evidence that fraternal birth order, familial co-occurrence of gender-variance, handedness, abuse, and mental rotation ability were related to adult gender-variance. Some previously untested biological and psychosocial variables were also related to adult gender-variance in this study: systemising, maternal age, and paternal cohabitation. The study was also able to confirm the factor structure of a number of latent variables and account for socially desirable responding.

These findings had implications for theories of gender-variant identity

development. Specifically, in accordance with Docter’s (1988) theory, it was found that biological and psychosocial variables tended to occur on a continuum between

participants with gender-typical identities and transsexuals. Participants with other gender-variant identities scored intermediary between participants with gender-typical identities and transsexuals. This research suggests the same biological and psychosocial factors are involved with the development of transsexualism and other gender-variant identities.

There was also no evidence that biological and psychosocial factors differed between gender-variant birth-assigned males with different sexual orientations, as Blanchard’s (1989b) theory predicts. Blanchard’s theory suggested that sexual

orientation was paramount in understanding two different etiologies of gender-variance: rational choice amongst androphilic birth-assigned males and autogynephilia amongst non-androphilic birth-assigned males. This research shows similar biological and psychosocial variables regardless of sexual orientation.

These findings build evidence for a biological predisposition to gender-variant and gender-typical identities with the strongest evidence for genetic and prenatal hormone effects. Any psychosocial determinants of gender identities are likely to be complex and work in interaction with biological factors, although further research is required to explore whether different developmental pathways can be observed from these biological and psychosocial variables.

This thesis makes an important contribution to our understanding of the

development of gender-variant and gender-typical identities. This study was the first to examine a large number of biological and psychosocial factors relevant to the etiology of gender identities in one sample. It included factors that have been linked to gender

identity development in the past and explored new variables. Unlike previous studies, the present research included multiple factors predicting adult gender-variance in a regression-type model. Although past studies have identified a relationship between a single biological or psychosocial variable and adult gender-variance, the purported causal relationship may have been hidden or suppressed by the relationship between other biological and psychosocial variables (Cohen et al., 2003). By including a number of biological and psychosocial variables in this study, this problem was minimised. In addition, this research was open to all participants, making it one of the first studies to include participants from the entire spectrum of gender-variant identities. It was the first research to assess whether biological and psychosocial factors are the same for

transsexuals as for participants with other gender-variant identities. It was also possible to explore mean differences between transsexual, other gender-variant identity, and gender-typical identity groups.

One of the main strengths of this thesis is the large sample size (N = 2,277). The large sample size allowed the use of, SEM to model latent constructs. It was also possible to detect effects of small sizes. The sample size allowed for assessment of the validity of the latent variables using confirmatory factor analysis. By taking into account measurement error in the variables used in the study, a more accurate

estimation of the relationships between these variables and their predictive power could be undertaken. Invariance testing was also conducted to rule out findings of group differences being explained by measurement non-invariance. There was evidence for measurement invariance between participants in different regions (USA and

Australia/New Zealand), suggesting cultural differences in word meaning were unlikely to have affected the findings.

The large sample size made it possible to test for differences between birth assigned males versus birth-assigned females and different sexual orientation groups. Power analysis showed it was possible to detect small effect size differences between these groups. By using SEM, it was possible to assess evidence for the causal direction of abuse as an etiological factor. In addition, unlike most past research in this area, this research was conducted using a statistical technique that was robust to non-normality in the distribution of variables.

Research on this topic tends to rely on self-report measures which are

susceptible to response biases such as social desirability. However, social desirability was controlled for in the present study. This was the first study of biological and

psychosocial correlates of gender-variant identity development that has accounted for social desirability.

Table 9.1 summarises the contributions that the thesis makes.

Table 9.1 Summary of contributions of the research

This is the first research examining the development of gender-variant identities to: - examine a large number of biological and psychosocial variables to be able to

analyse these in a regression-type model to gain further insight into the true relationship of these.

- include both transsexuals participants with other gender-variant identities to assess whether biological and psychosocial factors are the same for these different groups.

- incorporate social desirability in a study of biological and psychosocial correlates.

- use SEM methodology and use estimation robust to violations of multivariate normality.

By improving our understanding of the biological and psychosocial factors related to gender-variant and gender-typical identities, this thesis deepens

understandings of the development of their gender identities. The results of this thesis have potential to aid clinicians working with people with gender-variant identities to understand their clients’ gender identity development. In turn, these findings may help persons with gender-variant identities to understand their own gender identity