We aren't just talking about sex, here, sweets... But that too. Staturatory rape, although actaully not mentioned in this book, is made into an issue when it isn't. RAPE is an issue, but statetory rape isn't, since there's no force invovled.
However, making the age 13 isn't going to help either. You have to take every single case by case. Was the personal mentally able to make their own decision? Not, How long have they been alive?