However, we do know that children DO suffer for the sins of their fathers (racism, wars, etc)... but that is from natural consquence, not God punishing them.
This is not the case with David's baby. It was specifically written that the child will die BECAUSE of the sins of his parents. That was the punishment.
And I'd say that god mandating that the Jews slaughter every Canaanite---it could also be argued that the wrath of that god was taken out on the children for some sins the parents must have done against a god and a law they did not even recognize. Kind of like Americans getting slaughtered in California for not showing proper respect for the laws and leaders of Afghanistan.
NC