Not sure this will contribute to the political analysis here, which is fascinating, but some observations from my professional life and from friends and family..
Used to work with ex-prisoners , and found quite a fluidity in sexuality and behaviour amongst prisoners.Many men who are straight on the out had same sex activity in prison, was an unspoken but not guilty secret in a way, just something that happened there but not when free.
Amongst women there seemed to be a greater proportion who discovered same sex activity AND RELATIONSHIPS in prison that were more fulfilling emotionally and sexually. They maintained that change when out of prison, and identified themselves as lesbian..as one said to me ''no more dicky for me, girlies all the way now''
Also friend has twin boys, and an older girl. The boys are physically identical, truly impossible to tell apart, but now at 17 one, who always played with clothes, dressing up and with girls, is now out as gay, while the other is macho personified with all 'manly' traits on full bore, as they sort of have been since childhood.
So, dunno what that says really, maybe for some it is innate from the beginning, whilst others have an element of choice...did Tom Robinson ever explain going from stridently gay to happily hetero married? (making some assumptions there..sorry)