At the risk of diluting an excellent node, I'd like to offer an alternative, more
dire, view of the breakdown of effects by age. Until the age of 6 or so, when
pimephalis points out that kids can begin to understand
external causes,
they internalize everything. If Daddy's gone, it's my
fault. If Mommy and Daddy are shouting, it's because they're
angry at me.
It's very important to minimize very young kids' exposure to anger, grief, violence and loss because they don't know it's not about them. I am not a psychologist, but I believe this period of uncertainty runs from birth to about 6 years rather than from 6 onward.