Chestnut
Doodledog You have just written exactly what I was thinking of writing. Are we telepathic? I was just reading about a woman whose husband announced he was gay (not bisexual) after 18 years of marriage and two grown up children. That fits your last comment.
Yes, Chestnut, it definitely happens. It's not really a case of someone being attracted to both sexes, but of changing from one to the other after, in some cases, a very long time of knowing that they are straight*. If people with this experience don't identify as bisexual, why should others have the right to label them as such?
All I'm saying, really, is that I don't think that the idea that people can't 'turn gay' is 'obvious' at all. I don't know, but I think it's unlikely that people can be 'turned' gay, and certainly not in the way Section 28 claimed would happen if they were 'encouraged' by gay teachers, but I do think that people's sexuality can change over time.
*I haven't come across a case of it happening the other way round (ie from gay to straight), but there is no reason I can think of why it wouldn't.