yes, i saw an egyptian kiss his child son on the lips in a documentary, and there is many lip kissing in movies about southen american families. but i think it's sick, no one should exchange liquids but hasbands and wives, and you can't be sure that lips are dry, yuk.
i mostly will not be able to answer your reply, since marissa mayer hacked my email, no notification

Families are different. I know people who kiss family members on the lips, age notwithstanding. As far as I'm concerned as long as no one is getting slipped the tongue then why should it be weird.

Open or closed-mouth, it is bizarre to a son to kiss his mother on the lips when he is older than 5 or so.

That kiss was tricky (on the edge of their cheeks and mouths) to establish subtlety the the sick love from the Jessica's character to Jonathan's. That's the same case when she washed him as if the son were another breeding horse.