"There is no one alive who is youer than you."So said Dr Seuss, who could have added "and there never has nor ever will be, too." Your genome, the total collection of DNA that resides in your cells, is yours alone for all of human history. That precise remix of your parents’ DNA will never be repeated, even if you are an identical twin.
We are in the era of the genome, where reading this unique coded script is easier than ever. For £100 you can exchange your spit in a tube for an analysis of your ancestry or your risk factor for various diseases or traits, or even your likelihood of sporting success. In my opinion, these are at best trivial – and at worst a form of astrology – but they’re alluring enough to indulge our solipsism and predisposition to crave simple answers to complex questions.
Genetics is really only the formal scientific study of families and sex. But everyone has a family and everyone is interested in sex. We’ve been observing and codifying patterns of inheritance throughout human history: the first piece of medical advice based on inheritance is probably in the Talmud, with special dispensation being given to a small proportion of Jewish boys who are permitted to avoid circumcision on the grounds of their being at risk from what we now call haemophilia.
We learn these patterns of inheritance at school, but we now know that they are actually not nearly as clear as we once thought. Eye colour is the classic example: there is a gene which determines blues or browns, and browns are dominant over blues. But there’s another gene for green, and so far, 13 other genes have been shown to have a significant effect on eye colour. It is effectively impossible to predict the colour of a child’s eyes, based on their parents’, and every combination of parent and child is possible, including blue-eyed parents making brown-eyed kids.
And so it is for all genes and all human characteristics. We long for narrative simplicity, for a simple line of cause and effect, as elegantly easy to understand as a family tree, or a will. In that sense, we are culturally programmed to misunderstand genetics. We now know that as Seuss points out, genomes are uniquely complex, and with everyone’s experience being unique, too, human variation is infinite. We know that most diseases and traits are governed by many – dozens, sometimes hundreds – of genes, in concert with every unique life lived.
So DNA is not a blueprint, or an instruction manual, as it is sometimes described. Your genome alone won’t reveal your personality, or explain your behaviour. It won’t tell you how intelligent, how tall, how violent, how beautiful, you will be, nor what gender or sexuality or sport you will prefer. We are more brilliantly, frustratingly, complicated than that. I learned recently that people bearing the name Rutherford have a motto: Nec fato nec sorte – by neither fate nor chance – which is oddly fitting.
The human genome is an epic sprawling saga that culminates in you. In it there are tales of your ancestors, of the history of our species, of disease, famine, culture, and a lot of sex.
Now we put this new science together with some older intellectual pursuits – history, archeology, paleoanthropology, psychology, medicine – and begin to paint a more complete – but never finished – picture of how we came to be what we are. The genome is a history book, now open to interpretation, and as long as there are people, our exploring will never be at an end.
*** Based on Guardian UK
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