Wrong. While it is true the Scots less mixed than the English and the Irish,this is only true of the "Highland Scots". They are the ones that kept to themselves,and were originally Picts. From what I have seen and heard,they get along with the Irish better than the lowland Scots. The "purest" blood in on that little island are the Welsh. There are DNA matches between some of the local villagers there and pre-historic remains that prove those blood lines have remained in that one area for thousands of years.
BTW,my own RH factor is neither + OR -. People who have type A blood with either can use my blood,and I can take transfusions from either group.
As for the RH factor...take that up with the person, who began all of this stuff. Just don't expect to get a rational answer, as he doesn't know what he's talking about. :-)