4 year age gap

I’m currently seeing this 25 year old and I’m 21. Mind you we both just turned this age in the beginning of the year. Somehow my family thinks he’s too old for me which doesn’t make sense. I mean I can understand to a point because 21 and 25 year olds at different stages of life. But we are both pretty mature so I don’t see the issue. Sometimes he does talk about settling down, so that’s the only thing I’m worried about. But I know that I wouldn’t do anything just because he wants to. Like I understand that my career, goals and life comes first before anything. Do you guys think he’s too old for me?? What are some of your experiences with age gap relationships?