Wilko, I'm probably not fortunate to see redheads here, I've seen maybe 4-5 redheads in whole Poland, fair-haired are more visible (one of those redheads was a Kashubian, we had a nice talk about Slavic matters :) ). I don't know. However, it's true that more the closer to Ireland, the more red hair occurs. Red hair is associated with Celts – map of their historic settlements :


You can see redheads in the streets of Slovakia (at least in my region, btw. there is a Celtic hill-fort in my village), I remember redheads from the high school, but of course they are rare. Czech rep. has more redheads, IMO there's most redheads in percentage of all Slavic countries.

Redheaded Jews? Well, here Jews are not associated with red hair, they are too dark to have red hair. I heard about this combination in the TV for the first time.