Max well, you think a Bar Mitzvah kid is an adult? So, you would have no problem with your 13 year old son getting married?
I have already written about that. One is responsible for his at age 13 and this does not have anything to do with getting married.
Years ago girls got married by 12-13 and boys by 16.
In fact gypsies still get married by that age too.
Today we get married later because we want more out of marriage than years ago and we need to mature before we realize what with what kind of person we want to be married to.
However even if a person is not mature enough for marriage at age 20, they are still responsible for their actions. These are two seperate things.