Violence or Sex, which is more Evil?

As featured on slashdot.org, it is being reported the ESRB has pulled the 17+ rating of GTA: San Andreas and re-rated it at 18+. This is due to a 3rd party patch that unlocks a mini game that involves having sex with your girlfriends. In full explicit^* pink polygon detail!

Now I don't particularly mind what rating GTA is. Its probably a game that young kids shouldn't play but I think the onus should really be on the parents who buy these things to take at least some interest in the content of the game. What surprised me was a game that is essentially about amoral criminal activity including indiscriminate murder is apparently fine for 17 year olds but as soon as there is a hint of sex involved that bumps the age up by a year to 18+ (aka Adults only). Am I the only one who thinks the ratings people have their priorities the wrong way round?

*explicit as in not as explicit as Sex in the City after the watershed. If you really want to see what the fuss is about go here.