11
May

What is an X DNA Match on Family Tree DNA?

Do you want to know what it means to have an X-DNA match on Family Tree DNA? In this post, learn the answer, as well as how to figure out how your X-DNA match is related to you.

X-DNA matches can provide clues into aspects of your family tree that you might not have known otherwise. In addition, the unique inheritance pattern of X-DNA can give you details about how you may be related.

Family Tree DNA is a great DNA testing service and the website allows us to view in-depth details about our genetic connection to our matches. It might seem complicated at first, but this post will give you the information that you need to make sense of your X-DNA matches.

What does it mean to have an X DNA Match on FTDNA?

If you have an X-DNA match on Family Tree DNA (FTDNA), it means that you and your match share at least one identical DNA segment on your X chromosome.

Your X chromosme is one of your sex chromosomes. If you are female, you have two X chromosomes, and if you are male you have an X and a Y chromosome.

In other words, if you have an X-DNA match on FTDNA, you and your match share identical genetic material on your sex chromsome.

For males, the meaning of a match on the X chromosome is more straightforward. Males don’t inherit X-DNA from their father, which means that the X-DNA shared with a match must have come from their mother’s side.

Females inherit X DNA from both their mother and father. The X-DNA that they inherit from their father came from their paternal grandmother, as the grandfather did not pass down X-DNA to his granddaughter.

X-DNA inherited by females from their mother came from a complete X chromosome passed down from their father, and a recombined X chromosome passed down from their mother.

How are you related to your X-DNA match on Family Tree DNA?

In order to figure out how you are related to your X-DNA matches, more study of the way X-DNA is passed down is necessary.

Males and X-DNA matches on Family Tree DNA

We already know that males can eliminate their entire paternal side when searching for possible connections. In other words, an X-DNA match cannot have come from their father’s side.

A male can look to his mother’s lines to find how he might be related to his X-DNA match. Understanding the inheritance pattern can help us further eliminate potential ways that males are related to their X-DNA matches.

Since a male’s mother inherited X-DNA from both of her parents, we can’t eliminate them. But, we do know that a male’s paternal grandfather did not pass DNA down to his grandson.

For me, it helps to draw a simple family chart on paper. This way, I know which lines of the tree an X-DNA match could possibly be related on.

Depending on how large the shared X-DNA segment is, I might not need to go very far back on my chart. Once I have narrowed down a few lines, I can compare those surnames to the male’s X-DNA match’s family tree.

If you haven’t yet started building a family tree, definitely check out my book which is a guide to family tree building basics.

Females and X-DNA matches on FTDNA

Since females get X-DNA passed down from both of their parents, we don’t get to easily eliminate 50% of our ancestors as possible connections like we do with males.

The same basic inheritance pattern holds true for females, however. When I’m trying to visualize X-DNA in my head, I get a little confused.

Excuse my “chicken scratch” handwriting below, if you will. This is the type of drawing I will often make (again and again) when researching my X-DNA matches.

The female DNA tester inherited X-DNA from both of her parents, as indictated by the (X) next to the ancestor’s name. We can see that NO X-DNA got passed down from her grandfather.

If it’s a close X-DNA match, we might already know which surnames to compare. It’s especially helpful if you have access to your DNA match’s family tree information, if possible.

We can go further back in our chart, too, to eliminate more possibilities in search of a common ancestor.

If we draw out the chart adding another generation, we will see that a female could have inherited X-DNA from:

  • Her father’s maternal grandfather
  • Her father’s maternal grandmother
  • Her maternal grandparents
  • Her mother’s paternal grandmother
  • Her mother’s maternal grandparents

If you want to, you can print out a pedigree chart from your tree and trace the inheritance of X-DNA back, eliminating potential lines and surnames.

Then, compare your tree to your X-DNA match’s tree in order to find common surnames. The common surnames could indicate how you are related to your X-DNA match.

You can be related to your X-DNA match in more than one way

You can be related to your X-DNA match in multiple ways. If you share autosomal DNA with your DNA match, you could have inherited it from the same common ancestor that passed down the X-DNA to you.

Alternatively, you could be related to the DNA match in two or more ways, meaning the X-DNA was passed down from a different common ancestor than the one who passed down the autosomal DNA.

This issue also occurs with autosomal DNA matches.

Conclusion

I hope that this post has helped you understand more about how to understand your X-DNA matches on Family Tree DNA and how to figure out how they might be related,.

If you have any questions about something that you read in this post, or if you have any additional questions about your X DNA matches on FTDNA, please join us in the discussion below.

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