View Full Version : Determining genetic distance

08-25-2013, 06:23 AM
i guess this question may have been asked several times, but here goes, how does one determine genetic distance and is it possible to determine in a time lines, as in number of years?
A member on ysearch has a very close match with my 67 marker results, is it possible to determine how many years ago those couple of markers that make the difference may have changed??

08-26-2013, 05:33 PM
Without getting into the complexity of multiple step mutations, Genetic Difference between two Haplotypes can be determined by summing the difference in values of the 2 profiles being considered. If you are referring to your own profile recently posted on a different thread - Ysearch ref W25R4 compared to Irvine Ysearch ref H7JJM, 64 of the values on your 67 markers match Irvine's. The 3 markers that don't match have a difference in value of 1 so the Genetic Difference (GD) between yourself and Irvine is regarded as 3 on 67 markers.

Both of you have a high probability of belonging to the R1b-U106 Haplogroup. I suggest you go to Ysearch and look for matches to yourself using 67 markers and look for matches using the option with say 57 matches. You will find a number of matches including N5PA5, the U106 Modal. If you compare the three haplotypes you can print them or preferably copy/paste them into Excel where you can identify the differences with coloured cells.

Comparing you and Irvine with the U106 Modal you will see that you and Irvine share 5 or 6 differences with the U106 Modal. It is highly unlikely that these ''off modal mutations'' occurred independently and it is much more likely that you and Irvine share a much more recent common ancestor who also had these values. It is probable that one of you have 2 mutations from you common ancestor and the other has 1 i.e. genetic difference = 3. As a rule of thumb if you can consider that a mutation will occur on a 67 marker profile on average every 6 generations suggesting that your common ancestor lived approximately 12 generations ago.

08-27-2013, 10:06 AM
Hi, thanks for this, helps quite a lot

08-27-2013, 01:40 PM
A GD of three between two people is the sum of mutation between the two back to a common ancestor. A 67 marker GD3 divided by two equals 1.5 gd's times 172 years per mutation (MarkoH 2012 rates) is about 258 years before the current generation, about 8.6 generation back to a most recent common ancestor. Reconsider any difference with Multi-copy marker allele values that have a greater than one and treat it as only one GD ( infinite alleles model)