That is not something I consider when breeding in my own herd because I have never come across a bad tempered chinchilla. Chinchillas who have not been handled and are afraid of humans are not bad chinchillas and it doesn't affect their kits. The only negative behavior I will remove from my herd is pee shooting on humans. This is taught to new babies and can ruin them. I breed 100% for health, fur, size, and color.