Red Hair, Jewishness and the 45th Parallel

I've came across a few little curios regarding the rouge tint recently. Firstly this on Wikipedia;

"Red hair is also fairly common amongst the Ashkenazi Jewish populations, possibly because of the influx of European DNA over a period of centuries. In European culture, prior to the 20th century, red hair was often seen as a stereotypically Jewish trait: during the Spanish Inquisition, all those with red hair were identified as Jewish. In Italy, red hair was associated with Italian Jews, and Judas was traditionally depicted as red-haired in Italian and Spanish art."

Then also this article that suggests there's a link between red hair and the 45th parallel. It's a good piece and basically points out that beneath the 45th parallel it becomes disadvantageous to have red hair because of the increased amount of sunlight. Food for thought.