Drinking age is 21. We're called adults since we're supposed to have better judgment then teenagers. Giving alcohol to a minor is a crime. If the parents want to press charges, that's their choice and right.
What, if after downing a few jello shots, these 14 year old girls wanted to have sex your friend? After all it's their choice, and your friend had been drinking, so it's not his fault, right? The girls were bugging him for it, so he's absolved of all responsibility, right?
Bad decisions have consequences. If you're lucky, the parents won't drag your butt into this, since it was your party. If you're not lucky, I hope you have a good lawyer.