So much depends on the individual cats, but I have found that, in general, neutered males are the most tolerant of each other. Females tend to be more territorial and less apt to accept other cats in the household, even if they grew up together. There are exceptions to every rule, of course, but this is the conclusion I've come to after having serial multiple cats in my life.
Right now we have four neutered males in the house, and they all tolerate each other and even like each other to varying degrees. They often play with each other, sleep together, eat together, and share the same space. The only time we get any hiss-n-spit type stuff is when one cat wants to play and the other one doesn't. But we've never had any serious fights amongst them.