We don't have that problem in the Netherlands, why would it be any different in the USA?
More importantly, how did you get that info? Did you take part in a scientific experiment?
NL parents allow their teenage kids to have six freely, hence the low teenage pregnancy rates, the parents give them condems. This is a nightmare for most other countries in the world, morally.
It's the equivalent of saying "we can't control drug use, so lets just give them drugs" - youth suicide rates are up 50% in the last 5 years in NL, everybody is on antidepressants to deal with the depression that comes from dropping moral fortitude.
On the other hand, US gun death rates are dramatically higher than the rest of the world; same problem reversed.
So the logic stands:
Acceptable violence = more violence (obvious problem)
Acceptable free-for-all six = more six (problem, with not so obvious repercussions)