The specialized Peloran we call Spaceborn were built to fight in extreme environments that would kill other humans. Even other Peloran. They can survive deadly cold and even walk in vacuum without pressure suits. Though they do still need to breathe, so their standard uniforms include spare oxygen storage and breathing masks. This allows them to remove the internal air from their starships before combat as a tactic to reduce the effects of explosive decompression. Their eyes can see far beyond the standard visual spectrum as well, and they can look directly at a sun without being blinded. Even when in vacuum. The most interesting bit is that these defining traits of the Spaceborn are dominant. After two thousand years of manning the Peloran border patrol with a constant slow trickle of new recruits from the homeworlds, most children of mixed ancestry favor the Spaceborn traits over those of their groundbound brethren. Some may have the disabilities of normal eyes or skin, but they are a distinct minority in the Peloran border patrol that makes up their primary naval forces.