Is it possible to join a scottish highland clan even if I have no relation to them?

I love the scottish culture, people, music, and everything about them but I'm an American and I can only figure out that my heritage goes as far back as pioneer days (I'm guessing a lot of them died or my ancestors didn't record who the babies came from) I'm hoping I have some relation to Scotland, being that I have slightly green eyes and my Dad says his family is from Northern Europe areas. But I have searched and I can't find any clans that have the last name Riches as a possible surname for families within the clan. But can I join one?