Here's a list of "G" rated movies for 2012 and years past:
http://www.movieinsider.com/mpaa/G/
To each his own as far as choosing and allowing one's children and grandchildren to see the movies they see, as we are the ones responsible for them and will have to deal with any aftermath. I allowed my then not quite 2.5 year old grandson to see "Deathly Hallows 2" last summer, he LOVES Harry Potter! He caught some of the underlying funny stuff in the movie that other theater goers didn't, and when he laughed when no one else did many soon followed, I think because they realized he "got" it. He had no problems after seeing it.
It's really just a matter of knowing your child(ren), not their age as much as what they personally can handle. Truthfully, I have more problems with what he hears from my 11 year old nephew who thinks the stupidest stuff (IMHO) is funny and cool :-/