I know this is old but here is my thought.
Socrates how was gay once said that if all people were raised "gender Neutral' 50% would be bisexual.
What I believe is that about 50% are gender neutral "what sex they find attractive" It is the gender training that pushes them in the direction of preferring the opposite gender. It is our society that forbids us being gender neutral. So if you change gender male to female some will come out. It is not necessarily the female hormones and anti male hormones that does it. Many are on hormones for a long time and it is not untill they live as women that they find men attractive, or at least they are not turned off so much!. But with some just taking female hormones they find they are "checking out men" to their surprise. This does not mean you were gay as a man and did not know it. Also and this is my thought "It is natural to want to be normal" So as a man you find women attractive then suddenly as a women you find men attractive, as well as women. For me I just would find it "wrong" to be a lesbian but I do not find men attractive. If I suddenly found myself as a women I would not doubt date men even have sex but cannot see myself wanting to be with one. I doubt i would find their body's a turn on.
I have read many a posts of transgender women suddenly finding themselves attracted to me after starting hormones and living as women. Personalty I think it is the brain readjusting gender thoughts to your new body.
