I would not presume to say that all or even most gifted kids do this, but I think my ds8 falls into this category.
I am assuming you mean physical affection - hugging, wrestling, arms around shoulders, etc.
From what I have read and can tell from experience, there are touchy-feely people and those who are not. Gifted kids do tend to take things to extremes. So, if you have a gifted child who happens to be touchy-feely, and that child is learning for the first time (or second or third) how to conduct and express themselves in a friendship, things can seem a little lopsided. The kid on the receiving end can start to draw away making the whole thing seem even more lopsided.
I do believe this sort of affection between friends who are boys is even less welcome, even at the tender age of 5 and 6.
How to curtail it? I am not really sure on that one, I think it is a pretty delicate situation.
I never felt right teaching my ds that hugging other kids, boys or girls, was not a good thing.
DS has grown out of/learned to understand where and with whom he can get most physical. He is still pretty physical with DH, me and his sis. I would hate to make him feel like this is bad - it does seem to be part of his nature, not something he's going to completely stop all around.
I imagine this trait will go a long way towards having a happy wife and kids, at least
