I've no idea whether there exists any link between Scottish heritage and premature grey, but my Kilpatrick forebears all went completely white-haired in their twenties. I was a little more fortunate, with only significant greying in my thirties. I'm in my mid-forties now, and still not completely grey (but getting there quickly). And thankfully, balding is not an issue in my family.

Keep in mind that Scottish genes are just a mish-mash of a bunch of European genes. Or, more correctly, the gene pool in Scotland contains genes from Ireland, England, France, and many more.