I have had some fighting issues with 2 of my 3 year old littermate brothers. Someone recently told me the reason is because I kept the stray Mother cat and all 4 of her kittens, that by nature, they would all go their separate ways, especially the boys, to territoties far away from each other. But because I decided to keep the Mother and all her kittens, that I have caused them to live under stress. Any thoughts on this?