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Recent Updates

GEDmatch incorporates the relationship predictor from!

You can read here about how GEDmatch is now using the most accurate relationship prediction probabilities on its One-to-Many tool. You can also use the free tool here. Other relationship predictors are only applicable for Ancestry data. They were developed from that company’s simulations, for which we have never been provided a methodology. Being only from one particular company that uses the half-identical region metric, other relationship predictors are also unusable for 23andMe sibling data. GEDmatch has made a wise choice! 

A three-part series on using the kits of multiple tested relatives

Almost everyone who has siblings tested and used them in a WATO tree was doing that wrong until recently. I explore several methods and find that all of the best methods are ones that approximate the amount of a parent’s DNA that the children have, when combined:

Part 1: The Theory

Part 2: Testing the Methods

Part 3: Empirical Data

The first ranges of X Chromosome DNA

If you’re interested in X Chromosome DNA, be sure to check in with this article from time-to-time as I update it with data for additional relationships. This is the only place to find shared X-DNA ranges. Data for great-aunts/uncles, half-great-aunts/uncles, and 2nd cousins once removed are now available.



This relationship predictor uses the most accurate data currently available and shows differences between maternal and paternal relationships.

multiple cousin PREDICTOR 

This tool is the same as the above relationship predictor except that it includes 3/4 siblings and double 1st cousins—the first tool of its kind.

AYPR/ROH Predictor

After using the GEDmatch “Are Your Parents Related?” tool, the best thing to do next is to enter the cM amount directly into this tool.


How much of an ancestor’s DNA do you have? How much would you be able to reproduce if you and various relatives all had your DNA tested?


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