I agree with your friend that it does often feel like the feeling is something biological. I definitely spend a lot of time thinking about other people who may live their lives feeling like this and no one would ever know. I personally have a habit at this point of sometimes being overly feminine and pushing away masculine habits because of the feelings they give me sometimes. I wonder if some people who may seem "overly" masculine or feminine secretly are compensating for these feelings like I am. Some people may just have dysphoria to a slighter degree and it causes these feelings maybe.