Genetics, politics and murders. Who ever thought such a day would come?
Have you been following the American politics lately? Ever heard about the senator Elizabeth Warren?
Wait! Wasn’t this supposed to be about science? How is American politics related to science?
Well, it turns out Elizabeth warren has claimed to have taken a “genetic test”, to prove her origin to be native American.
Is that even possible? Proving your origins through a test?
Yes, in fact mankind has developed ways and means to do so; genetic genealogy.
Genealogy? What does that even mean?
Genealogy is derived from the Greek words genea and logos, meaning generation and knowledge. Genealogy is the study of one’s family history or origin; tracing back their lineages.
Family tree. Image from flickr
Genealogists use the genetic makeup to understand lineages.
Genetic genealogy is the practice of using DNA testing to identify one’s ancestry or lineage.
Back to the basics
Our DNA is neatly packed in structures called chromosomes. We humans have 23 pairs of chromosomes in total. Of which, 22 pairs which we call the autosomal chromosomes and the 23rd pair, the sex chromosomes. Females have homologous X chromosomes as sex chromosomes, while males have a X and a Y chromosome.
Among the 23 chromosomes one of each pair is derived from both the mother and the father’s chromosomes.
The blame game. Image by Ludie Cochrane from flickr.
In male, the sex chromosome consists of an X and a Y, where X is retrieved from the mother and Y from the father.
In females, sex chromosomes consist of two X chromosomes, each from both the mother and father.
Mitochondrial DNA is another set of DNA present in the power house of the cell. This DNA is inherited exclusively from the mothers and passed down to her child.
Depending on the kind of ancestry question raised, Y-DNA test, Mitochondrial DNA test and autosomal DNA genetic genealogical tests can be done.
How does genetic genealogy testing work?
The different genetic genealogy testing companies (like 23andme and AncestoryDNA) have a DNA extraction kit which is used to extract DNA sample(like cheek scrapping or chewing gum) from the client who is curious about their origin. They match the DNA to their own repository of DNA samples derived from previous testings.
These companies have their own repository of markers identified from previous tests stored in the database. The companies match the samples or “markers” to their previous data.
Markers are mostly the SNPs (Single Nucleotide polymorphism) found in the DNA. This SNPs might be exclusive for a particular ethnic group which will be helpful in identifying them.
The findings that come out from the testing is more or less provide answer to the question, “in the current scenario where does your DNA come from?”, and not the “past of the DNA itself”.
This being the major drawback of the tests, provides varied results when testing using different providers.
Moreover, we all inherit parts from both our parents. The 23 chromosomal pairs have been received one half from the mother’s and the other half from the father’s chromosome. During recombination, half of both the maternal and paternal ancestry is inherited, not the complete ancestry.
At the same time, these tests might reveal half the truth about your ancestral origin, but not the entire truth.
There have been many instances of such excruciating scenarios, revealing a part of one’s ancestral origins.
Another pitfall of such test is, it can’t be replicable. That is, every genealogist who test the same sample, have to come out with the exact same inference, which is not the case as of now.
With more inputs to the genealogical databases, eventually the results will be more accurate and replicable more so.
Genetic genealogical testing might not seem to be helpful in finding your true origin, it has been perfectly put to use in forensics, solving murders.
If you ever want to know more about your ancestry, International society of genetic genealogy wiki is a place to start.