I was actually repeating what was said in a video I watched yesterday so I went to look at their sources - here is a relevant study that supports this conclusion - https://www.sciencedirect.com/science/article/abs/pii/S1743609515339060

However while looking it up in google scholar I did find another study that concluded the opposite, that there’s no significant difference between identical and fraternal twins. That study is here. https://www.nature.com/articles/s41598-022-17749-0

So it’s possible that I was misinformed.

As a bonus, here’s an interesting analysis about what even is gender and gender identity in an academic setting. https://academic.oup.com/analysis/advance-article/doi/10.1093/analys/anad027/7204699