If someone has red hair, does that mean they definitely have ancestry in Scotland or Ireland?
No. The genes for red hair most likely developed 70,000 years ago and have been a minority trait ever since in Asia and Europe. Ancient texts describe red hair in Celtic groups and areas near the black sea, Balkans, and Egypt. Some or many Thracians and Scythians had red hair. DNA taken from ancient British and Irish shows that they mainly have darker skin and brown hair and blue eyes. There were several migrations later from groups like the Yamna and from from areas around the black sea and Russia that brought red hair to the area after 5,000 BC. ……..
https://www.quora.com/Are-there-more-redheads-in-Ireland-or-Scotland