@FusionxtrasFusionxtras, if you read the newest chapter ( this is just a theory btw I might be totally bullshitting idk) his father insists on saying he doesn't have a brother but the sister is saying he exists and they're blood-related. My theory is that the brother we know now lost his memories somehow, and the father is trying to keep the "bloodline pure" if that makes sense. Idk it's a theory though, so I might be totally wrong.