I'll start with a little back story:
Bf and I split up and I met this guy, we will call him "C". We were just FWB no feelings ever. Got back with my boyfriend and C became just a friend.
3 years of being friends now and we hang out regularly. I had a baby in 2016 and went to visit C when baby was 9 months old. I went to the bathroom and when I came out he was holding baby and just talking to him. For some reason seeing him hold my son was a huge turn on and if I wasn't with my boyfriend I would have slept with him.
No idea why seeing him hold a baby was such a turn on. Guess it was seeing him in a father role maybe. Seeing guys with a baby is always attractive to me.