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X Chromosome Inheritance

For example, the chart for a woman's X DNA inheritance shows that she inherits 25% (0%-50%) of her X DNA from her maternal grandmother. This means that on the average, a woman inherits 25% of her X DNA from her maternal grandmother, but could inherit as little as 0% or as much as 50%. The chart also shows that a woman inherits 50% (50%) of her X DNA from her paternal grandmother. This means that a woman inherits exactly 50% of her X DNA from her paternal grandmother. These charts ignore the possibility of Y crossover, which doesn't seem to contribute significantly to X chromosomes.

The charts are pdf files that may be printed. There is a blank area next to each ahnentafel number where you can write your ancestor's name.

Most of the charts include blank boxes for ancestors that do not contribute X DNA to the descendant.


The percentage of ancestors who can contribute to a person's X chromosome DNA decreases with each generation.
See: X ancestor percentages by generation


I've written a program that finds blocks of matching SNPs in pairs of men in Ben Moscia's spreadsheet.
The program output is here:
Blocks of matching SNPs

You can download Ben's spreadsheet here.