here is what i have found to be true: the more time my children spend together, the closer they become. the more time they spend apart (with friends) the more irritable they become to each other. i find that fascinating - and quite revealing - don't you?
woah, this has ended up kinda long but i have been really grateful lately for our large-ish family and that our children's best friends also happen to be their siblings.
and just wanted to share that it IS possible for your children to be best friends before they're in their mid-20s :)