There is a link between kids seeing violence too early in their lives and actual violence, yes indeed. However, if VGs didn't exist, there are countless other ways: movies, books, the internet etc..that kids can view inappropriate material. I don't play VGs but I doubt they are any worse than a Frank Miller movie/novel. Ultimately, it does come down to parents and other responsible adults keeping violence images away from kids until they are old enough to understand the gravity of it. There are too many adults out there who think that video games ( and comics ) are still the mild, 1980s versions. That's not so.
The only area in which I've had a problem with the VG industry is arcades. Those places are a haven for young people and most VGs are appropriate. Yet I've seen violence VGs in the middle of them and that is irresponsible. I'm not sure if only the specific arcade is blame or if the VG producers do/should have control over where arcade games are placed.