Well, I don't think I would write them as Americans anyway, so I'll probably hold them to different standards :/ Writing them differently would just feel to awkward for me.

Heh? Why couldn't Seth be the son of a man/woman who values very highly, but is an atheist. Or Darwinist? Or socialist? Or communist? They could teach him the same sense of duty and conformity. Especially the communist. I don't see how religion would play such a big role there.