Yes unless the parents still have any authority. The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.

Is it bad for a 18 year old to date a 29 year old?

Depending on the situation, it can be inappropriate for an 18 year old to date another 18 year old, or a 29 year old to date another 29 year old. Judging purely on the age difference, I dont think its inappropriate at all because legally theyre both able to consent in most of the world.