Talk:Rule of 1/1000 common ancestry

They are all averages, with wide ranging possibilities
The "50%" from each parent is exact, but what you get from an earlier ancestor, even a grandparent, can be as low as 0%. So you can get anywhere from 0% to 50% of your genes from one particular grandparent. The 25% is only the average likelihood; it's only just more likely than 24% or 26%. -- Robin Patterson (Talk) 00:01, March 22, 2013 (UTC)