I have 4 girls who couldn't care less about each other most of the time, unless there is a threat-strange cat at the window, dog visiting (especially small dog
) then it's all for one and one for all, or a trip to the vet (can't tell where one cat starts and the other stops in the big carrier-best friends
I had a boy and a girl littermates who loved each other when they were kittens, but then he played too rough for my girl, and she wouldn't even let him wash her head after a while, no matter how sweet he tried to be. I think it just depends on the cats, and who can tell for sure when they're so little or before they have time to sort it out!?!
Unless someone else knows the answer to that question,(if you do, please tell!) I'd just get kittens/cats who are really close in age and size, with personalities you like, and go for it.