I had a two homosexual confess to me that they liked guys more than women, then they started becoming gay. I do believe some are born gay, but I believe is default state of unnatural occurrences.
Liking guys more than women means that they were already bisexual favoring guys.
Not surprising that they'd go with that.
And it mostly isn't a choice. One of the smartest persons I've ever met told me what being homosexual was like, and his experience was exactly inverted from mine, all his life: he notices guys, he just doesn't notice girls.
Not by choice, by how he has always experienced reality.