I'm only attracted to my little girl, actually. I don't fantasize or think about sex with anyone other than her. But before her, I was solely attracted to men. She came along, though, and that was very much changed. Though I do list myself as "heterosexual," I am actually more "open-minded," because gender is not a deciding factor for me in who I am attracted to. It certainly wasn't when it came to my little girl.
It was a bit hard to deal with for me, being attracted to a female, because I had always identified as homosexual, but it was also easy because I had fell in love with her so badly.