@ Hayden Clark
There is a legally enforced ratings system for games as well. Has been for a very long time.
Hence Jack Thompson's complaint against Best Buy for not asking his son for ID when Halo 3 carries a rating... In the UK, for example, it falls under the BBFC '15' rating as evidenced by the big graphic on the front, side and back of the box.
Those claiming to be completely normal despite having played age-restricted games whilst well below that age are making an entirely different point, whether they acknowledge it or not.