Most people are cisgender, meaning that their gender identity corresponds with their birth sex; however, some people are transgender, meaning their gender identity and birth sex are different. Increasingly, scientists have been working to help us understand what accounts for this gender variability, and research suggests that the answers may have to do with both genetics and the brain.

Our friends over at ASAP Science offer a brief review of what the research in this area has found so far, which you can check out in the video below. As you’ll see, there’s some research to suggest that being trans runs in families. Also, some studies have found that the brains of trans persons are more similar to their identified sex than their birth sex (e.g., a transwoman’s brain seems to have more structural features in common with the brains of cis women than cis men).

However, and this is one quibble I have with the video, they don’t address the fact that a lot of these studies are based on very small samples (which means the reliability of the results may be questionable). There have been some inconstancies in the findings across studies, too (perhaps stemming from reliance on small samples). Also, in many of the brain studies, the trans participants were on hormone therapy, which raises the question of whether the brain differences observed preceded hormone use or were a product of them. That’s a really key factor we need to disentangle in future research.

Check out the video to learn more, but do keep the limitations in mind. This is an area where a lot more research is needed before we can draw firm conclusions.