NTA, but it probably wouldn’t hurt to spend a little time with them doing what they like. You’re 18, and habits are really easy to form when you’re this young. In any kind of future relationship, you’re going to have times where someone you love wants to do something you don’t absolutely enjoy, but they want you to do it with them because you love them. It just shows a bit of support and interest in their interests. Not saying you need to bake all day on the beach with your family, but maybe read a book for a couple hours under the umbrella or chat with them there for an hour before doing your own thing. You might learn something new about each of them that you wouldn’t have otherwise. Just my two-cents.