My dad was 45 when he had me, yours was 18. I had the opposite experience because my parents were so much older than my friends' parents. I think that's the biggest part of what you're seeing: your dad is just younger than your friends' dads.

But to your broader question, there is no way a person is "supposed to act" at a given age, but there are some norms. For instance, a lot of folks who party a lot in their teens and twenties get bored with that at some point. Also, working to earn a living to feed the family often leaves people more with out and preferring something quiet at home to going out with a bunch of people.