House cat hunting has nothing to do with whether or not they are well-fed. They hunt because of instinct and training by their mothers. And it is true that females are generally more likely to hunt. This is because females are the ones who provide for their offspring. Also, sometimes cats who do not hunt were removed from their mother before they were weaned and could learn to hunt. You said your cats were brothers. Could this be the case?
I've only had one cat who didn't hunt, and he was a male whose mother died before he was weaned, so he was raised completely by humans. I swear he waved and said hello as cockroaches walked by him. Drove me nuts, but we also have a female who lives to hunt and I would just call her. The male cat would watch amused as she caught the bug, but never really seemed to be interested in doing the same.
I've only had one cat who didn't hunt, and he was a male whose mother died before he was weaned, so he was raised completely by humans. I swear he waved and said hello as cockroaches walked by him. Drove me nuts, but we also have a female who lives to hunt and I would just call her. The male cat would watch amused as she caught the bug, but never really seemed to be interested in doing the same.
