My GP asked me the same when I first told her I was doing DIY hormones. Incredibly gender affirming, but shows that even medical practicioners can be pretty clueless about it.

I had a transmasc asssume that hormones did the work both ways as well, he at least knew how it worked on testosterone.

damn, i wish

I learned how puberty works for both estrogen and testosterone in school. So I knew what each hormone would do if you had them. I just didn't know about hrt for a long time.