How Do DNA Tests Connect Us?
This is one of those questions that come up time and again. So many times we get new matches who think you’re related only on their maternal side of the family at 23andMe (and sometimes at FTDNA). Why is that and what can be done about it?
If you have taken the 23andMe test, the first results you get back are your haplogroup types. Both men and women get maternal haplogroup info through mtDNA, and men additionally get YDNA hapologroups. This tends to confuse many people, especially women, and leads them to believe they are only going to get matches on their maternal side. 23andMe needs to do a much better job of informing their customers that their mtDNA is not the basis for their Relative Finder matches. But until they do, here’s a summary of what I posted earlier on 23andMe.
Types of DNA
1. Everyone has 3 types of DNA, Autosomal, Sex determining and mitochondrial
A. Autosomal DNA controls almost everything about you EXCEPT your sex and sex linked characteristics. It encompasses chromosomes 1-22. You get one copy of each chromosome from each parent so you have two chromosome 1s, two 2s, two 3, etc. The DNA from the two matching chromosomes undergoes mixing, changes frequently, and is used to trace close to moderate distance relatives from both sides of your family.
B. Sex Determining chromosomes are X and Y. Women have two X’s and no Y, men have one of each. Men get their Y from their fathers. Men get their X from their mothers. Women get one X from each parent. Since the Y only undergoes sexual mixing at the ends, it stays almost the same for a long time (hundreds of years) and can be used by men to trace their surname line. The X chromosome undergoes mixing every time it passes through a female and can be used for tracing close to moderately distant cousins on both sides of your family for women and for the mother’s side of the family for men.
C. Mitochondrial DNA is outside the nucleus in the female egg. Sperm have no mitochondria. All your mitochondria are handed down from your mother’s mother’s line. Because mitochondria doesn’t undergo mixing, it stays the same for a very long time. The mtDNA line is rarely useful for finding close matches as it can be unchanged for thousands of years but it is good for tracing the migrations of ancient prehistoric populations.
What Companies Test What DNA?
FTDNA tests your mtDNA, Y DNA (for men only) and autosomal DNA *family finder* as separate tests. Family finder is the test that allows you to match both sides of your family looking for close to moderate distance cousins.
23andMe tests them all in one test. Your relative finder matches come from your autosomal chromosomes plus the X and can be from either side of your family.
Ancestry only tests autosomal DNA and uses it to give you your ‘DNA’ matches. Those matches can come from either side of either of your families.
Filed under: The Basics