🚀 go-pugleaf

Regarding the request for info on what gender of kittens get
along best....  personally, I think there's a lot more 
between-cat variation than between-sex variation.  That is,
I think some males are playful, some standoffish, some hostile, etc.
etc.

But I strongly believe that kittens from the same litter who grow
up together have the best chance of being good friends.  I have
two six-year-olds who grew up together; they wash each other, play
together, come to each other's rescue ... they're spayed females.
Actually, from the same litter is nice, but the main thing is that
they grow up together.  Two kittens from the Humane Society of the
same age would do nicely, too.  I think you have to observe the
kittens involved to determine some of their personality traits, to
see if they're congenial or what.

Introducing a kitten to a cat can be disastrous!  I have an adult
cat who was permanently traumatized by the unflagging hostility she
experienced from an older cat, when she was a kitten.  After three
months of hating the kitten at full force, the cat ran away.

Good luck.  - Anne