I guess this thread is not going to get a lot of traffic because there are very few samples from Luxembourg in FTDNA's database (at least, as far as I know).
I know of two: Gommes (7VEN3) and Conrardy (6C3G6).
Gommes is R-U152 (untested for the sublcades, I believe), and Conrardy is R-L21*... R-L21* is 50% of the R1b1b2 in Luxembourg! ;-)
I didn't think much of this but a suggestion was made to me that has some possibilities.
Could R-L21* be prominent in among descendents of Flemish peoples? Technically, Flanders is in Belgium but I think this part of Europe, Benelux, needs to be considered together.
There are only four 67 STR confirmed L21+'s in Benelux. Two have the 11-13 Combo (406s1=11 617=13) signature. Conrardy (6C3G6) is one and the other is Ammerlaan (4YRVX) of the Netherlands. There is no proof that all of 11-13 is a clade, but sections of it may very well be.
An 11-13 researcher, Ann S, suggested that several DNA connection with some people in Ireland (where my genealogy goes) and the Scottish Borders have a common theme of Anglo-Norman or Cambro-Norman connections.
The Welsh contingent of this group is centered in Glamorgan, which is directly connected to some of the others' folklore and Norman incursion into Wales.
The researcher has now recently suggested the possibility that the scattering and folklore add up to a possible Flemish origin, that is a Flemish element of the Norman invasion/immigration.
I know little about the Flemish. What are their origins? Were they remnants of a Zone Beaker expansion? or other cultural expansions? What haplogroups seem to be common of Flemish people?
BBC on Flemish Colonists in Wales:BTW, we have a Swede and a German in the 11-13 Combo variety as well.
Geraldus Cambrensis, Itinerary Through Wales, 1188: The inhabitants of this province (South Wales) derived their origin from Flanders, and were sent by King Henry I to inhabit these districts; a people brave and robust, ever most hostile to the Welsh; a people, I say, well versed in commerce and woollen manufactories; a people anxious to seek gain by sea or land, in defiance of fatigue and danger; a hardy race, equally fitted for the plough or the sword; a people brave and happy.
BBC on the Norman Impact in the Scottish Borders: After the invasion of 1066, the Normans set about introducing their laws and customs to Britain, first in the south of England, formalising land ownership, reforming religion and increasing trade. Land was granted to Norman, Breton and Flemish nobles who had been part of the conquest..... The Scottish Borders were the focus of many of the reforms."
http://www.bbc.co.uk/legacies/immig_emig/scotland/borders/index.shtml