First of all, if you have done any Y-DNA testing at FTDNA and not already done so, I would strongly encourage you to join the R-U106 Haplogroup Project https://www.familytreedna.com/public/U106 We also have an active forum which you may want to join (send an email to
[email protected])
We are still in our early "infancy" in regards to linking SNPs to cultures. It must be remembered SNPs are actually linked to families, and not cultures. Families can be found across cultures (think of how many families were split by the U.S. Civil War into the North & South) and cultures consist of many families.
R-U106 was undoubtedly found in the population of "Norman" settlers to England. It must be remembered the Norman Conquest also included a significant Flemish component (as William's wife was from Flanders) and the Low Countries were a "hot spot" for U106.
In addition, Lowland Scotland was repeatedly settled by the Flemish in the centuries after the Norman Conquest. Several of the Scottish Kings actively recruited them to emigrate, so it would be hard to prove a R-U106 ancestor arrived in "the Isles" from the Norman invasion, or if they arrived during a later settlement.