'Fay Folk' was pretty common a while back too.
Meh just date a redhead, and when sexy time rolls around just exclaim, "MOSES! I HAVE FOUND THE BURNING BUSH!!!"
Comes with the genes. Fair complexion, light eyes (typically) and red (and/or light) hair. And yes, the Celts were both light and dark. Welsh were sometimes referred to as 'Black Irish' because of the dark, wild hair and olive skin. Sometimes, almond shaped eyes. 'Fay Folk' was pretty common a while back too. My Gran was from Wales, adopted out of an orphanage there. Had pitch black hair 'til the day she died and a beautiful olive complexion. Interesting enough, her name was Olive.