Dear Dr K,
To what extent are my personality traits — for example, my love of thayir vadai, my laziness, my aversion to elephants — determined by my genes, and to what extent have they come out of my life experiences? I am having a hard time figuring out exactly how much blame I can pass on to my parents for all my flaws, and how much credit they should get for my virtues.
Deter Minn
Dear Deter,
The question you are asking me has been the subject of much debate in psychology, neuroscience, and philosophy. It is the nature versus nurture question: how much of our character and behaviour is programmed by biology, and how much of it is formed by various external influences that we are subjected to from birth? I wish I could just tell you it is entirely the former or the latter, because that would be an easy answer to give and you could then put away this column satisfied in the knowledge that you understand the source of your own characteristics.
Everyone knows that, by and large, there are certain traits that are inherited genetically: your height, the colour of your eyes, your predisposition to certain kinds of disease, and other purely biological factors. But what about things like your cheerfulness, your susceptibility to addiction, and various other aspects of your personality?
We prefer to think that for the most part, our personalities are not inherited, but developed during the course of a lifetime. If you are a nervous person, you probably wouldn’t blame your nervousness on your genes, and you may try and boost your confidence by the sheer force of your will (good luck), or through counselling, meditation, or some other psychological means like wearing a batman costume wherever you go.
However, a relatively new field of science called behavioural epigenetics is investigating the possibility that instead of considering nature and nurture as two separate forces, there may be a very significant overlap between the two. Studies in behavioural epigenetics are revealing that major life experiences, like the trauma of abuse or war, can affect not just the individuals who actually live through them, but their children and grandchildren as well.
The way in which a person’s genes express themselves in an individual can be altered by the occurrence of ‘molecular scars” in the form of methyl groups that attach themselves to the DNA. These methyl groups are generated during a person’s lifetime, if they undergo a traumatic or particularly uplifting experience, and may be inheritable for as many as a hundred generations. There are still several questions that remain to be answered, like exactly what kinds of experiences generate these scars, and if some of these epigenetic changes may be beneficial instead of harmful.
What scientists do know is that if your shyness or pessimism or predisposition to depression can be traced to methyl groups that stick to your DNA, there can be a molecular cure for your personality problems, a way to clean your DNA of all the generations of life experience sticking to it. The only issue is, when you wipe the slate clean, you might end up getting rid of the good with the bad.
Yours questionably,
Dr K