Deep Ancestry: DNA Testing & Heritage

It took me a few weeks to decide that I didn't want my DNA for a graduation present. The thought had been tempting me ever since I'd attended a lecture about genetics with my AP Biology class; apparently there were companies who, for as little as a few hundred dollars and a cheek swab, would mail you a map of your ancestral origins based on bits of your DNA. I'd always loved history, but felt I wasn't a part of it; to me, being white and American meant you weren't connected to anything, even though I technically knew some of my “ancestors” had come from Ireland and Scotland about two hundred years ago. I wanted to send off my DNA samples and receive a map telling me that in fact, I was a combination of all sorts of interesting backgrounds. It would have validated my place in history, in my own mind.

I ended up not doing it, but I still plan to one day if I somehow have $300 to spare. (That's the cost of the most expensive kit at the DNA Ancestry Project.) (1) However, researching the Ancestry Project and signing up at the website made me stop and question what I was getting myself into. Why did I feel the need to know where my DNA came from? And what difference would it make? How, exactly, could a bunch of people in lab coats take scrapings from my cheek and turn it into a map saying my great-great-great-great grandparents had lived in...well, wherever?

DNA itself is surprisingly simple stuff. It consists of four nucleotides – adenine, thymine, guanine, and cytosine – strung together in two long chains with alternating phosphate and sugar “backbones”; these two molecule chains wind together like a ladder to create a double helix shape. Because enzymes use DNA to build proteins, DNA is often considered the “blueprint” for a living organism – DNA acts like genetic “instructions” that dictate how an organism will be put together. (2) For this reason, no two organisms have the exact same DNA (except identical twins and cloned animals), since every organism is slightly different.

Additionally, there exists in some organisms (including humans) another kind of DNA, called mitochondrial DNA, that is present in tiny organelles called mitochondria and is passed down from an organism's mother only. (3) The mtDNA is almost identical through the maternal line, whereas an organism's “regular” DNA is inherited half from the father and half from the mother – with the exception of the Y-chromosome, which only males inherit and much of which remains unchanged from father to son. (4)

Since certain portions of the Y-chromosome and most of the mtDNA do not change over generations, these two forms of DNA can be used to check for a common ancestor paternally or maternally simply by how close they match. Two individuals who share the same mtDNA or Y-chromosomal DNA probably share a common ancestor, though how far back that ancestor was must be estimated by further analysis. (Women who are seeking to trace their paternal ancestry must supply a Y-chromosome sample from one of their close male relatives, since they don't possess this genetic information themselves.) For normal chromosomal DNA, geneticists use chromosomal patterns called haplotypes to determine where an individual's ancestors came from. Haplotypes are “regions of chromosomes that have not been broken up by recombination, and they are separated by places where recombination has occurred” (5); this means they are bits of ancestral DNA that have been shuffled and reshuffled by sexual reproduction into different combinations among different populations over time. By comparing the geographic spread of different haplotypes, one can determine where a set of DNA came from hundreds of thousands of years ago, and whether two individuals shared a common ancestor. The more markers (areas of the chromosome) a specific DNA test analyzes, the more accurate the results – and the more markers that two individuals share, the more recent their common ancestor. Results like these can be used for researching specific genealogies, for forensic investigations, or simply for providing a person with information about where, in general, their ancestors were probably from.

I realize that this technology isn't perfect; everything with DNA breaks down to probability rather than provability. However, it opens up new and interesting possibilities for claiming a cultural heritage; I might not just be from Great Britain, but all sorts of interesting places. Haplotype mapping also helps put together stories about how the human population has migrated over thousands of years and could help to identify which portions of the human genome increase the risk of different diseases, such as cancers.

In researching this technology, however, I found that haplotype mapping also raises ethical questions I hadn't even considered. The International HapMap Project, for example, postulates that “researchers may find that a genetic variant associated with a higher-than-average risk of a disease is more common in one population than another,” which then “may be misinterpreted to mean that every member of a group has a higher-than-average risk of the disease, even though the higher risk may apply only to those individuals, inside the group or out, who have that variant.” (6) Genetic discrimination could come into play with insurance companies; a company might charge more to cover a person who has a haplotype associated with a high risk of a chronic illness like diabetes, even if that illness never manifests itself. They could also be targets of discrimination in the workplace, where employers might not want to hire someone with, say, a higher-than-average risk of cancer.

The idea of discrimination by DNA is interesting because while discrimination has traditionally been based on race and gender, “the information emerging from the [International HapMap] Project is helping to demonstrate that common ideas about race emerge largely from social and cultural interactions and are only loosely connected to biological ancestry” (6); however, it seems possible that genes and haplotypes could replace race as the primary method of discrimination if DNA testing becomes commonplace and individuals' haplotype maps become available to others. While I don't feel that this potential discrimination is a reason to curb advances in DNA testing technology – the medical and scientific benefits outweigh, in my mind, the potential risks – it is important to take these possible negative effects into consideration, and to legislate privacy rights which will hopefully keep this sort of thing from happening.

As for me, I still really like the idea of having my haplotype markers analyzed. In the grand scheme of things, I doubt it will make any difference to anyone, but in the short-term, it would give me a new perspective on my body and my life. I realize now there is a lot more to DNA and genetics than just getting a printout in the mail, but at the same time, I want to see that map of where my ancestors probably lived and migrated to. So much of the human experience is based on choice and decisions about how one wants to be, but I feel it would be interesting to see a part of who I am that I can't change – that, no matter what choices I make and what environmental factors come my way, will always be an inextricable part of who I am, and who others before me were.



(1)The DNA Ancestry Project. [http://www.dnaancestryproject.com/index.php]

(2)“DNA: Physical and Chemical Properties.” Wikipedia, the Free Encyclopedia. [http://en.wikipedia.org/wiki/DNA#Physical_and_chemical_properties] 17 December 2006.

(3)“mtDNA.” Genetic DNA Glossary. [http://www.clanlindsay.com/genetic_dna_glossary.htm]

(4)“Y Chromosome.” Genetics Home Reference from the National Institute of Health. [http://ghr.nlm.nih.gov/chromosome=Y;jsessionid=E08860AEBFD0E58ED766FE844F97C806]

(5)“Origin of Haplotypes.” International HapMap Project. [http://www.hapmap.org/originhaplotype.html]

(6)“Ethical Concerns.” International HapMap Project. [http://hapmap.org/ethicalconcerns.html]