A new study led by researchers from the Hudson Institute of Medical Research in Australia has identified 12 significant genetic differences between transgender women and non-transgender males. It is hypothesized that these genes, known to be involved in sex hormone signaling, possibly contribute to a person's ultimate sense of gender identity.
The study analyzed the DNA of 380 transgender woman, compared to a control of 344 non-transgender males. The results identified twelve functional genetic variants in transgender women correlating with genes involved in regulating the sex hormones estrogen and androgen.
"This is the world's largest and most comprehensive study examining changes in genes that control sex hormone signaling in transgender women," says lead author on the study, Vincent Harley. "It identifies several new genes or genetic variations never before looked at in gender dysphoria."
The new study is part of a growing body of research examining the possible biological origins of gender identity. Earlier this year a team from Augusta University presented some results from a yet to be peer-reviewed study identifying a number of genetic variants suggested to play a role in transgender identity.
Another study, again presented in early 2018, examined brain activity in transgender children. The results claimed the MRI scans revealed patterns of brain activation in the transgender children that more closely resembled their desired gender, as opposed to their biological sex.
An even larger study that sets out to comprehensively examine the genomes of 10,000 subjects (of which 3,000 are transgender) is currently underway. Spanning five institutions across Europe and the United States, this work is again on the hunt for genetic markers that can offer clues to a biological origin underpinning gender identity.
These studies are undeniably provocative, with much debate still circling over questions around the origins of gender identity. In an interview with ABC News in Australia, Sally Goldner from Transgender Victoria fairly sums up the pros and cons of this kind of scientific essentialism.
"It's good to see [the research] back up what we already know — that we are who we are," says Goldner. "It's not so good if people don't seem to fit some sort of genetic test, if that was ever developed."
Vincent Harley certainly agrees that the goal of his research is not to reduce gender identity to a simple genetic origin. Instead, he hopes the work helps to lessen discrimination and distress experienced by transgender people.
"What makes you feel like a male or female is complex and involves interactions between many different genes, much like height, weight or blood pressure," says Harley. "However, while genes play a role, they are not the only factors involved in determining gender identity."
The new research is published in the Journal of Clinical Endocrinology & Metabolism.