X Chromosome Inheritance
There is a box for each ancestor in the chart that includes
- 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.
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.