X Chromosome Inheritance

X chromosome inheritance for a woman

5 generation chart (1 page, with empty boxes)
6 generation chart (2 pages, with empty boxes)

X chromosome inheritance for a man

5 generation chart (1 page, with empty boxes)
6 generation chart (1 page, no empty boxes)

their ahnentafel number
their relationship to the descendant
the average percentage of X chromosome DNA that the descendant will inherit from them
the possible range of X DNA percentages that could be inherited from them is shown in parentheses

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.