People of Germanic or Celtic origin are the most likely to have red hair. When I was young with a head full of hair and traveled to Germany for the first time, a woman walked up to me at a train station and asked a question. I knew enough German to respond convincingly that I didn't speak German very well. She was astonished because she had assumed that I was a native.
Having red hair, unfortunately, poses difficulties -- and I don't mean a tendency for sunburns and skin cancer. People with red hair are often teased, sometimes to an ugly extent. This has been going on for centuries, and it continues. Wikipedia reports that a British supermarket was forced to withdraw a Christmas card that had the image of a red-headed child sitting on Santa Claus' lap with the words "Santa loves all kids -- even ginger ones." (Ginger is UK slang for red hair, light skin, and freckles). I would have been offended if I had seen that card. Actually, the very idea offends me.
This morning I shopped at Costco, and the check-out clerk had red hair. I smiled at her and said that I liked her hair. More important is what I didn't say: I hope she likes it herself.