The genetics for both are recessive in complex ways that aren't fully understood. But like the article says recessive does not mean diluted. For example the genes for red hair are quite widely distributed across central Asia. Every once in a while you'll get an Arab, Turk, Persian, Kazakh, Mongolian or even Tibetan or Han Chinese person born to two dark haired parents but the kid has auburn-brown hair, or light eyes - though usually more grey than blue.
One thing that has become clearer from recent DNA sequencing of ancient remains is that all the human visible variation is quite new: we'd recognize none of the human ethnicities or subpopulations or whatever we should call them, of 10,000 years ago. For example it seems Britain in the late mesolithic was inhabited by a short stocky people with dark skin, dark hair, and blue or grey eyes.
One thing that has become clearer from recent DNA sequencing of ancient remains is that all the human visible variation is quite new: we'd recognize none of the human ethnicities or subpopulations or whatever we should call them, of 10,000 years ago. For example it seems Britain in the late mesolithic was inhabited by a short stocky people with dark skin, dark hair, and blue or grey eyes.