It is not illegal for a 16 year old to date a 20 year old. The age of consent in Massachusetts is 16 for all types of sexual contact. However, until you turn 18, you are a minor and your parents can legally forbid you from seeing people

What happens if a 16 year old dates a 20 year old?

Its generally legal for a 16 year old and a 20 year old to have sex in OK.