Rus, no it’s really not about a developmental moment.
They are not far from finding genetic links to being gay or straight.

http://abcnews.go.com/m/story?id=4529843

I do have a sibling who is lesbian and she tried to date guys but nothing ever clicked for her until she kissed a girl. (God, I hate that Katy Perry song.) It seems that for so many it really is a question of you are or you aren’t.