HaKatan: I clearly made a distinction in my first post. I said if you don’t know your cousins that well then it could be true. I just said that by people who grow up with their cousins it isn’t necessarily true.
Obviously, people can be Over Issurim with cousins, just like I said earlier that it’s possible to be Over Issurim with a sister or a mother. The fact is, though, that by cousins (for most people), Stam talking between cousins does not <i>inherently</i>carry the same assumption that the main reason you are talking is because the person you are talking to is a member of the opposite gender. If one talks to their cousin in an Assur fashion, then it’s Assur. But if they don’t, it is not <i>inherently</> Assur.