Attraction I might even understand, I just can't imagine the headfuck the guy might feel sometimes. If at all. I mainly feel sorry for the kid that's gonna come. If people decide to fuck within the family, whatever but they shouldn't have kids. There's always the chance they'd start fucking them too once they're legal too
Genetically, the baby is the grandson's and some other woman's, but I feel sorry for it too.
I don't believe they will ever molest the baby but the whole thing with the grandmother having sex with her grandson creeps me out and it's likely to creep out anyone in the child's life who finds out about it, so I think that would be a good reason to leave kids out of their incestuous relationship.