I will try to explain my question of the STR variance. Take for example a fixed territory, let’s say an idealize Gaelic Tricha cet (30 hundreds) with its thirty Baile biataig (estates or hundreds) ruled by a nominal Ri (king). (The Tricha cet would be sub-divided into a number of Tuath (equated to Gaelic parish size), each with their own Taiseach. While the rulers of Baile biataig were the lowest level of nobility, with the Baile biataig holding their Derbfine (his close male relatives i.e. of same surname).) Assuming a constant population (i.e. typical state of affairs) with equal male and female (fighting and childbirth taking their toll.) Add the tribal culture of the Gaels, where chiefs of the Tuaths would have multiple wives and plenty of sons. (Sixteenth century English observed the excess sons of Gaelic chiefs as a source of instability, too much aristocracy chasing too little land.) What is going to happen if a tribal world existing in this idealized Tricha cet. The lower orders will disappear for being on the bottom of the heap (cannon fodder, famine and lack of reproduction). The prior levels of nobility are going to be swamped by the new aristocracy being pumped out by the chiefs. What does this mean for Y-DNA, within this closed world Y-DNA from the ruling line will constantly be disenfranchising (eliminate) the lower branches from the stem and hence reduce the STR variance by removing these alternative branches of the stem. I believe this can be seen in O’Clery’s Book of Genealogies (an in the Gaelic pedigrees in general). In O’Clery out of the 300 lines under Cenel Conail, 184 lines are concern with the different branches of the O’Donnells. The rest of Cenel Conaill is covered by 116 lines (of which 64 are to do with the O’Doherty family). The O’Donnells and O’Doherty in rough number account for 83% of Cenel Conaill section, or put it another way: The descendants of Stena m Ferghusa cennfhoda m Conaill ghulban m Neill noighiallaigh take up 296 lines of the Cenel Conail section, compared to 3 lines for the descendants of Boghuine m Conaill gulban m Neill and 1 line for the descendants of Duach m Conaill gulban m Neill. The section should have really been titled descendants of Stena instead, for descendants of the many other grandsons of Conail gulban are non-existant and so is their dna. What I guess I am trying to say is that the variance in STRs is also a reflection in the variance that the population being measured underwent. Such effects as the Gaelic tribes being top heavy with newly minted aristocrats (forcing the removal of lower branches) or the effect of the sixteenth and seventeen wars of English re-conquest and modernization with their typically quoted mortality rates of 50% (compared to Scotland’s population morality of ~9% in the War of the Three Kingdoms and England much lower again). I would expect a different cultures like feudal England to reflect different levels of variance.