Peter, It's a crap shoot - really. For any given part of your parent's DNA you have a 50/50 chance of which chromosome parts you get, and your sister does too. What you got has no bearing on what she got. Any particular area has 4 alternative versions: A. you got it your sister did not B. you both got it C. she got it and you did not D. neither of you got it. On average for all of your DNA, those 4 will be about 25% each; but on any particular chromosome, there are often wild swings. If you like playing with the math - in total, or any chromosome: A+B=.5 B+C= .5 A+B+C+D=1 (where 1 is the total for two sets of autosomes, or two chromosomes, depending on which you are looking at; 0.5 would give you one set of chromosome, or all of one chromosome) You'll find A=C and B=D in all cases; A can range from 0 to .5. Have fun, Jim Bartlett On 10/30/15, Peter J. Roberts via<genealogy-dna@rootsweb.com> wrote: For example my father's chromosome 3 (which he got from his mother) from 50 million to 80 million is most similar with persons from Iberia.à My father's chromosome 3 (which he got from his father) from 50 million to 80 million mostly matches people from Scandinavia.à Is it likely that area of my father's chromosome 3 will appear to mostly match people from "Northern France" (because it is between Iberia and Scandinavia? If so, then my chromosome 3 from my father from 50 million to 80 million is most similar with persons from "Northern France".à Let us say all of my mother's ancestry is from Japan and the chromosome 3 which I received from her mostly matches people from Japan on the area from 50 to 80 million. What could my sister's admixture look like in that same area?à How might it appear different from mine?à Could she look mostlyà "French" and I look mostly east Asian from 50 to 80 million? Is there a better way to ask this question? Thanks and sincerely, Peter Peter J. Roberts[1]http://www.wikitree.com/ References 1. http://www.wikitree.com/