Is it normal for a girl to fantasize about her dad and for a boy to fantasize about his mother?

Do most moms know that their teenage sons fantasize about them? Do most or some woman have fantasies about their fathers, and where does this come from? I’ve never thought about sleeping with my dad in real life, but I have thought about kissing him. Is this weird or normal? Has anyone ever thought about this? I also know some guys who had sexual thoughts towards their mothers.