Object of the month: You’re not who you think you are

7 December 2010
 DNA fingerprinting. Neil Leslie/Wellcome Images
[object Object]
DNA fingerprinting. Neil Leslie/Wellcome Images

In our ‘Identity’ exhibition earlier this year, Wellcome Collection examined the scientific and cultural ways in which individuals establish who they are, and how they assert their differences with other people. Genealogy has always provided a powerful means to mould a sense of personal identity and belonging, and over the past decade, following the Human Genome Project, the study of ancestry has been enriched by the increasing pace and declining costs of DNA sequencing technology. In the wake of television programmes such as ‘Who Do You Think You Are?‘, of course, genealogy has become an ever more popular and accessible hobby.

In our permanent gallery ‘Medicine Now’, you can see a number of commercial DNA ancestry kits bought online by our curator Steve Cross. Steve bought them using nothing but his credit card and was not required to seek professional advice before making his DNA sequence available (Steve explains the process in this video). These tests provide a swab that is returned to the company’s laboratory with a sample of your DNA and is used to construct a genetic family tree based on a comparison between your DNA and sequences from living populations kept on the company’s database. Many of these tests claim they can trace your ancestry to a particular part of the world or society – an enchanting prospect, especially for groups longing, for example, to trace their roots back to a time before the upheaval of the international slave trade.

One DNA test on display uses your mitochondrial DNA sequence – an entirely different set of DNA to your ‘regular’ DNA, residing in your mitochondria, tiny organelles in your cells that provide your body with chemical energy in respiration. Because mitochondria are inherited exclusively down the maternal line, mitochondrial DNA is particularly useful for tracing maternal ancestry. The mitochondrial DNA of all living humans is thought to be descended from a single woman who lived in East Africa around 200,000 years ago, a woman named ‘Eve’ by geneticists. Eve is our matrilineal most recent common ancestor. She was not, as is often thought, the only woman alive at the time (as in the biblical Eve), but it just so happens that this otherwise unremarkable woman produced an unbroken line of female descendants. The test result – accompanied by obligatory certificate – comes with a story that depicts the possible life of one of Eve’s descendants, or Steve’s ancestors. It is a work of complete fiction, yet it is testament to our desire to grasp hold of our past, to take ownership of it and, most importantly, to show that our ancestors were human, just like us (forget the fact it plays out like a Palaeolithic episode of EastEnders).

Quite aside from the cost of such services and the many ethical issues they raise – should we be making our DNA sequences accessible to private companies, and who owns this information? – many ancestry tests are notoriously inconsistent. Since the construction of a genetic family tree depends on the limited number of sequences kept on a company’s database (limited perhaps due to cost or the inaccessibility of present-day societies), since populations migrate over time, and since the genetic variations used to ascertain ancestry can vary from company to company, it is quite possible to be linked to a living population you have little to do with. One personality who has famously fallen foul of the ancestry test is Oprah Winfrey, who was initially thought to have Zulu ancestry, a claim now questioned by geneticists.

Along with cloning and genetic modification, DNA sequencing provides another potent example of the double-edged sword brought by advances in medical science. While they open up new horizons of possibility, at the same time they bring into view new questions, challenges and ethical dilemmas.