Do you know of research on this? I have two gay friends with feminine speech and both are adamant that they don't choose to have this and would prefer not to. Each has their own theory as to why they have it. One suspects it might be (epi)genetic while another suspects its influenced by being raised by women. I can't buy the latter since many very masculine straight men were raised exclusively by women.
https://en.wikipedia.org/wiki/Gay_male_speech
The guy at 4:04 articulates exactly the same idea as I did above