Next in the ‘A-Z’ series is S for Sexual Orientation. Higher rates of psychological distress among sexual minorities is not due to shared genetic influences. In this blog, Kunle looks at applying genetic research designs to investigate the links between sexual orientation and mental health difficulties.
What is sexual orientation?
Sexual orientation describes the pattern of one’s sexual attraction over time. Traditionally, one can be gay (i.e., be attracted to the same sex as oneself, also lesbian for women) or bisexual (attracted to both sexes). Other sexual orientations are possible such as being asexual (no sexual attraction to any of the sexes) or pansexual (sexual attraction to all sexes and genders). However, because most of the research involving genetics are focused on those who are lesbian, gay or bisexual (LGB), I will focus on this group for here.
Genetics and sexual orientation research
Genetic studies have found that sexual orientation is influenced by many genes each having a small effect, as well as non-genetic processes. Genetic research has also been used to investigate the links between being LGB and the risk of experiencing mental health difficulties.
Sexual orientation and mental health
Unfortunately, it has been repeatedly shown that LGB individuals experience more mental health difficulties compared to those who are heterosexual (or ‘straight’ i.e., sexually attracted to the opposite sex alone). These mental health difficulties include high levels of depressive and anxiety symptoms (sometimes jointly called psychological distress) and substance use problems. Most research suggests that the higher rates of mental health difficulties among LGB individuals are due to ‘minority stress’. Minority stress refers to the negative experiences LGB individuals experience due to their sexual orientation such as discrimination, expecting stigma, hiding one’s sexual orientation and self-stigma.
Genetics, sexual orientation and mental health
However, another line of research suggests that the link between being LGB and psychological distress may be due to shared genetic factors. Using the twin design (see Thalia’s blog on twin methods) and genomic approaches, previous studies have found overlaps in the genetic influences on sexual orientation and those on psychological distress. Very loosely, this could mean that the same genetic factors that make an individual LGB can also make them more likely to be distressed and anxious.
In my recently completed PhD, I tested whether the higher rates of psychological distress among LGB individuals were due to shared genetic influences or non-genetic processes. My research indicated that shared genetic influences were not an adequate explanation for the higher rates of psychological distress among LGB individuals. Rather, this association is better understood as reflecting non-genetic processes (such as minority stress). By combining the twin design with genomic data, I was able to specifically show that the experiences of being LGB can cause psychological distress and that these experiences include experiencing more victimisation than heterosexual individuals. Interestingly, my research also suggested that experiencing psychological distress may make some LGB individuals more likely to acknowledge their sexual orientation, but this needs to be further studied.
The key take-home messages are that being LGB is influenced by several genes working at the same time but each having a small effect; and that the link between being LGB and experiencing psychological distress is due to non-genetic processes. It may therefore be possible in the future to greatly reduce this increased risk for psychological distress among LGB individuals by reducing minority stress and other burdens. However, more research is needed to understand exactly how the higher rates of psychological distress happen.
Ganna, A., Verweij, K. J., Nivard, M. G., Maier, R., Wedow, R., Busch, A. S., … & Zietsch, B. P. (2019). Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior. Science, 365(6456), eaat7693.
Zietsch, B. P., Verweij, K. J., Heath, A. C., Madden, P. A., Martin, N. G., Nelson, E. C., & Lynskey, M. T. (2012). Do shared etiological factors contribute to the relationship between sexual orientation and depression?. Psychological Medicine, 42(3), 521-532.
Oginni, O. A., Lim, K. X., Purves, K. L., Lu, Y., Johansson, A., Jern, P., & Rijsdijk, F. V. (2023). Causal influences of same-sex attraction on psychological distress and risky sexual behaviors: evidence for bidirectional effects. Archives of Sexual Behavior, 52(3), 1213-1228.
Oginni, O. A., Lim, K. X., Rahman, Q., Jern, P., Eley, T. C., & Rijsdijk, F. V. (2023). Bidirectional causal associations between same-sex attraction and psychological distress: Testing moderation and mediation effects. Behavior Genetics, 53(2), 118-131.