The most common misunderstanding - mtDNA

I just see so many misunderstandings on genetic genealogy and DNA test forums concerning mtDNA haplogroups, that I feel compelled to try to explain.

DNA testing businesses tend to dumb down a lot of information for their "audience".  I feel that this actually increases misunderstandings, and mtDNA haplogroups are a good example.  Rather than use the lengthy description mitochondrial DNA, or even it's shortened mtDNA, businesses describe it more frequently as Mother Line, or Maternal.  It misleads so many of their customers.  So let us put this straight:

  • A haplogroup is a  "combination of alleles at different chromosomes regions that are closely linked and that tend to be inherited together"  A series of mutations, that are inherited across generations.
  • mtDNA are a series of mutations within the DNA of mitochondria.  Mitochondria exist outside of a cell nucleus.  They have their own independent DNA, apart from the nuclear chromosomal DNA that dictates how we develop, what we are.  We all have mitchondria, in most of our cells.  They actually serve a function by processing energy.
  • As humans, we use nomenclature to group those mutations within a family tree of humanity.  My mtDNA mutations fall within Haplogroup H.
  • mtDNA cannot be passed on to future generations by males.  it is passed down to the children from the mother only.  I inherit H6a1a8 (my haplotype) from my mother, as do my brother and our sisters.  Only my sisters though will reproduce that mtDNA in their children.  My own children inherited the mtDNA of their mother, not mine.

So what does this mean in practice?

  • A Maternal / Motherline / mtDNA Haplogroup does NOT represent your biological ancestry.
  • A Maternal / Motherline / mtDNA Haplogroup does NOT even represent your mother's "half" of your biological ancestry.
  • For example, your father's mother most likely carried a different mtDNA.  Your mother's father most likely had a different mtDNA haplotype.  Only one of your sixteen great great grandparents passed down their mtDNA to you.
  • Instead, it acts pretty much as a single line genetic "marker" that can be traced only along one very narrow, single line of ancestry.  Look at the image at the top of your post.  Do you see?  Just one line of descent. It follows your mother's, mother's, mother line, and so on, all of the way back to a hypothetical "Mitochondrial Eve" 100,000 to 200,000 years ago.
  • It is not a tribe, ethnicity, or identity.  It is just the mtDNA genetic marker (Haplotype) that you inherited from your mother.
  • It is no good going onto mtDNA genetic genealogy forums and giving the names and origins of ANY direct ancestor, other than a woman (or her children) on that maternal line (mother's mother's, mother, and so on).
  • Forget surname studies.  In most western societies, and in many other's, the "family" name is inherited from the father - and follows a completely different course (Y-DNA).  Indeed, the surname of your true mtDNA ancestor changes most generations with marriage.  That is what makes this the most difficult line to trace with documentary methods.
  • Although difficult, it is the most true and secure.  Although secret or hidden adoptions can occur, the risk of non-parental events is much lower than for the strictly male line (Y-DNA).
  • Mitochondrial DNA mutates at a very slow rate.  This, along with the change in surnames most generations, can make it difficult to use successfully for genetic genealogy.  Many of the mutations are thousands of years old.  Alternatively, it makes it a valuable evidence for tracing ancient ancestry within a population.

That is all that I wanted to say.  it is a fascinating marker, but it is not representative of even 50% of your ancestry, it is not an identity, it is pretty irrelevant to surname (studies), it is inherited only down one narrow line - but all of the way back.

My earliest mtDNA ancestor with a surviving photograph.  My mother's mother's, mother's, mother (2xgreat grandmother), born Sarah Daynes in Norfolk, during 1845.  Her mtDNA would be H6a1a8.  Her mother was born Sarah Quantrill in Norfolk during 1827.  Her mother in turn was born Mary Page in Norfolk during 1791.  Her mother in turn was born Elizabeth Hardiment in Norfolk during 1751.  Her mother in turn (my 6xgreat grandmother) was Susannah Briting, who married John Hardyman in Norfolk during 1747.  If my documentary research along this line is correct, then Susannah inherited mtDNA haplotype H6a1a8 from her mother.

views

Tags

1 response
1600's time frame, I have an Abraham and a Hannah HardiMAN in Braxton family tree (by invitation, private) on ancestryDNA. Both paternal and maternal in colonial NC from time of American Revolution. Thank you for your writing here.