Are Kim Jong Kook and Kim Jong Min really brothers?

Kim Jong Kook has a brother named Kim Jong Myung. His brother is the director of a plastic surgery hospital. Kim Jong-min is Ko Yoo-tae's Kim Jong-min. He once suffered a severe head injury, so he looks stupid. They are just friends. They have appeared together in entertainment programs such as XMAN, Flying Little Shooter, and Hidden Singer. Together with members Ko Yota, they have sung famous songs such as Kim Jong Kook's "Poisoned" and "White Love".