Unless you are referring to something I’m missing, that’s the fault of other people, not the parents. And it’s changing for the better every day.
Well let me put it this way, kids get bullied for much much smaller things by their peers. Having two fathers would certainly be a major bullying matter. While I agree that bullying it unacceptable and should not exist, however unfortunately that is the reality of nature. I don’t know what is the evolutionary purpose of bullying but I would assume it is to cull out any deviation from the current norm of the species. Kids are much closer to animals than adults are and are not nearly as good at suppressing the basic nature for the sake of social norms. Even the best efforts of education of societal norms from parents/teachers in many cases cannot suppress the basic nature in kids.
I am not saying that any of the above-said is right. I am just saying it is the reality. There is no way to pre-program kids to suppress the basic nature and behave according the social norms from the very beginning.
Still I might add that even in practise kids are much better off with decent same-sex parents than abusing heterosexual parents.