My X Matches compared to my mother's X Matches

[ieldrensecan]

I have uploaded mine (F17298) and my mother's (F22508) Family Finder data (at-dna and x-dna) to GEDMatch.

A mystery to me is that I have far fewer matches on the x-chromosome than my mother and also have far smaller total cM (and largest segment cM) than my mother. A part from my match with my mother on the "X" - which is the expected 196 cM total - all of my x-dna matches are under 13 cM total and I have only about 20 matches where I share any x-dna at all.

My mother on the other hand has about 100 matches where she shares more than 30 cM of x-dna - she also has a highest shared x-dna of 81.7 cM (61.3 cM adjusted) with a largest segment of 17.1 cM for that match.

Cane someone please explain to me what is happening here?

Russell Smith

[mkdexter]

There are a few reasons for this.

First, FTDNA is not giving us properly formatted X raw data. It really only works when comparing FTDNA to FTDNA kits as it contains mismatched build data. FTDNA does not format it because they package it straight from their scanner and give it to us, and do not use it themselves for anything.

Second, if there is a question in your results - instead of using default settings use 7cM and 700SNPs instead.

Third, your mother has twice as much X DNA as you do (XX vs. your X) so she will have an opportunity to match more people than you will on the X.


Matt.