I am a woman. I have watched gay porn in the distant past out of curiosity on pornhub.. I found regular men in videos to be a bit unpleasant for me, but 'twinks' I could definitely stomach. I had no previous gay porn experience. Some of them are pretty effemenite. I think its not a result of porn but just your preference.
Even for straight men, the "teen" industy is booming. It is kind of common for men to fantasize about younger bodies in general, I guess.

I have no idea how one could kick this attraction/fantasy, though. D: