I'm going to avoid a family meal with my dad
Why would you want to avoid your dad?
I don't want to know what my dad is up to.
That sounds pretty mean. It is not okay to avoid someone for no reason. He is family so you should take an interest in what he might be up too.
I'm old enough to do what I want.
That sounds like an immature standpoint. If you are getting older then you need to learn how to be a better person.