Help me out here HBD anons. I heard an argument against race that went something like this

>human races exist because they are groups of people with similar genetically-based characteristics and are more prone to certain diseases
>by this logic why couldn't gingers be separate race when the share the same genetically determined characteristics and are also prone to certain diseases?

Is he right? Did /pol/ lie to me? How to counter this argument, /sci/?

(to janitors, this is not a troll, please don't delete this thread)