37-Marker Matches and What They Mean

Hi,

What happens when you test 37 markers? Does a match of 36 out of 37 markers, commonly abbreviated as 36/37, mean more than 23/24?

Here is some more information from Ralph Taylor on what matches mean when we have 37 loci or markers to consider.

37-marker matches get even more precise. For example, if you share 35, 36 or 37 markers with another Taylor (or someone with your surname, if you are not looking at Taylor project results!) then you share a common ancestor, probably within a genealogic time frame.

o A perfect 37/37: The chances are 90% that your TMRCA is <= 19 generations, >= 1530 AD; 70% prob. is <= 10 gen, >= 1760 AD; 50% is <= 6 gen., >= 1860 AD.

o 36/37: 90% is <= 32 gen., >= 1210 AD; 70% is <= 20 gen., >= 1500 AD; 50% is <= 14 gen., >= 1660 AD.

o 35/37: 90% is <= 45 gen., >= 885 AD; 70% is <= 30 gen., >= 1260 AD; 50% is <= 22 gen., >= 1460 AD.

However when you have 37 markers to compare, and you don't match 35 or more, such as 33-34/37: You share a common ancestor, but probably not within a genealogic time frame.

§ 34/37: 90% is <= 57 gen., >= 580 AD; 70% is <= 40 gen., >= 1000 AD; 50% is <= 31 gen., >= 1235 AD.

§ 33/37: 90% is <= 69 gen., >= 285 AD; 70% is <= 50 gen., >= 760 AD; 50% is <= 40 gen., >= 1010 AD.

When we get to 32 matches out of 37, or worse: You may share a common ancestor, but the probability that he lived in within a genealogic time frame is small. The 50% probability level for a 32/37 match is <= 51 generations, >= 735 AD.

For some of you, these discussions of probability and statistics are dull. However, they are necessary to understand the meaning of genetic genealogy. We will have future posts with specific examples. For now, consider that your surname is Taylor. You have a family tree with some degree of confidence. Your fourth cousin, another male Taylor descended from the same line also tests. Now, if you match 37/37 or 36/37, this suggests that the family tree is correct for both of you. If, however, your match is 32/37 or less, the family tree is not correct for one or both of you. Because two males from the same male line, only separated by 6 generations would not differ to this extent.

May all your genealogical puzzles be solved!

Lalia