porn has more to do with disobeying religious beliefs.. human societies in general have difficulty talking about sex, and it makes some of us uncomfortable. Until of course we get the chance to do it, then there's suddenly no problem.
As a society, do we embrace sex or hinder it during our development phase as a child? I'd like to believe schools actually believe in sex education, when in fact most don't really talk about what kids need to hear. Sex is cool but should be done safely
If we all want to do it, why inhibit it?
So does seeing porn / nudity while growing up hurt our development? I don't think so in the least. In fact if anything our curiosity won't be driving us nuts if we've seen what it's about.