There are many stages/grades within this homosexuality
Some are simply curious and after testing out the waters, so to say, either find it to their liking or dont and act accordingly.
Some are confirmed homosexual.
Some are bisexual, i.e they like both men and women.
so, the natural evolution of sexual behaviour of any man or woman who engages in a homosexual activity is not predictable, as I would say, is the unpredictableness of sexual activity of a hetero sexual who has engaged in her/his first sexual activity. Its not that simple.
Hope this helps