If the game contains sexual content then it's fair to say that 15+ should be the age allowed without restrictions.
In U.K. age of consent (sex) for both heterosexual and homosexual is 16.
Europe, France, Scandinavia it's 15.
Most TV and films even suitable for 12 year olds, contains rude language and sexual innuendo's.
I and my partner raised our children from children to now adults.
I didn't expect their teachers to raise them, nor did I expect anyone else.
I read a lot about the government telling teachers they should do this and do that with children to discipline them.
So why should a retailer monitor the age restrictions of games being sold when there is no law to make them.
I buy all the games for my son on amazon.co.uk and I purchased one from eBay.
They didn't make an inquiry to see if it was for me or my son.
Majority of adults don't play play station, xbox or pc games.