I have Tommy and Tuppence, from the same litter.

Over the weekend, I attended the RI Pet Expo, and was chatting with someone from one of the larger cat rescues in our area. They NEVER permit litter mates to be adopted together, as they tend to fight as they age. Doesn't matter same or opposite sex, no exceptions, litter mates can NOT stay together.

I'd never heard or read this. Anyone else?