Dear Ancestry.com DNA…
I often receive questions from our users or potential members regarding who can participate in a given test. Many such questions deal with lines that have been “daughtered out.” For example, a recent inquiry asked:
“I had my DNA tested for mitochondrial results, but I’d like to do the same for my father’s side. My problem is that I have no brothers, no uncles, and my father has passed away. Can my son take the test? Or would his results only give his father’s Y-chromosome information? Surely my son must have inherited some of my father’s DNA?”
Types of DNA
DNA provides our genetic blueprint which makes each of us unique and yet genetically similar to other family members and to a lesser extent to all humans in general. There are 2 major types of DNA useful in tracing one’s family history through DNA genealogy:
- Y-chromosome DNA (Y-DNA)
- Mitochondrial DNA (mtDNA)
Y-DNA
Y-DNA passes from male to male in a family. Location markers on the Y-chromosome are found in the Y-chromosome of males and are passed down from fathers to sons making it ideal for tracing paternal lineage. In many cultures, the surname is also passed from father to son. This fortunate coincidence is what makes tracing your paternal lineage through genetic similarities so powerful for genealogy. And because the Y-chromosome is passed largely unchanged from father to son, DNA results from a male participant today can be used to represent the paternal lineage dozens of generations into the past.
To test your paternal lineage you need someone on your male line to take the test. If you are female, you can recruit a brother, father, or paternally related Uncle or Cousin to provide the DNA sample to use as if it were your own. The key to remember in recruiting a “proxy relative” for the Y-DNA test is that the individual must be a direct line descedant of the ancestor of interest. Thus, a woman’s son would NOT be a candidate for testing her great great grandfather as her son would have received his Y-DNA from his father NOT her father.
mtDNA
Mitochondrial DNA , or mtDNA , is a unique kind of DNA found outside the nucleus of the cell in the mitochondria. Because mitochondria still replicate on their own, they need their own special DNA , which exists in a loop (unlike the strands of chromosomal DNA ). A cell can have hundreds or thousands of mitochondria. This unique factor and the rate at which the mtDNA changes make mtDNA a strong indicator of one’s ancient ancestral heritage. Mitochondrial DNA testing is very valuable for unlocking clues about your ancient ancestors. It can also be a powerful genealogical tool to eliminate possible relations through the maternal line.
Because a father’s mitochondrial DNA (mtDNA) is destroyed at fertilization, a child inherits only the mother’s mitochondrial DNA, thus preserving the maternal link to the ancient past. Due to this unique inheritance pattern, both males and females may directly contribute a DNA sample for testing the maternal lineage.
Should you have questions about a potential proxy or DNA test, please contact dna@ancestry.com.
Fascinating! About how long does it take for a DNA test and about what does it cost?