A more accurate view would be that it really is both. It's a social construct, but it's not fully arbitrary, being historically (and currently) used as a proxy

A more accurate view would be that it really is both. It's a social construct, but it's not fully arbitrary, being historically (and currently) used as a proxy for ancestry, and thus genetics. >That we divide not based on actual genetics but visible markers makes it a social construct This is going too far towards the other end. Physical characteristics stem from genetic variations, and consistent patterns in appearance are often linked to some shared ancestry. It's not the end-all, but it's hardly without cause either.