If you are really curious I believe there is genetic testing that can be done to determine cat breeds, but frankly, he will probably be called a 'domestic shorthair'. He's very handsome! He and his sister could technically be half-sibling the way we humans reckon it since kittens within the same litter can each have a different sire depending on how receptive their mother was when she was in season. Regardless of what breed he might be considered, he is one beautiful cat.