The Lottery Of Life

Ninth instalment - traits more or less heritable

In the past few instalments I have discussed traits that can be safely ascribed almost entirely to genetics. There are other traits, however, which are heritable to some extent.

Here is an extract from an academic paper that defines heritability.

 A central question in biology is whether observed variation in a particular trait is due to environmental or to biological factors, sometimes popularly expressed as the “nature versus nurture” debate. Heritability is a concept that summarizes how much of the variation in a trait is due to variation in genetic factors. Often, this term is used in reference to the resemblance between parents and their offspring. In this context, high heritability implies a strong resemblance between parents and offspring with regard to a specific trait, while low heritability implies a low level of resemblance.

          Estimating Trait Heritability Naomi R. Wray, Ph.D. (Queensland Institute of Medical Research, Brisbane, Australia) & Peter M. Visscher (Queensland Institute of Medical Research, Brisbane, Australia) © 2008 Nature Education

There is no consensus among scientists as regards the extent to which personality traits are heritable. It seems inconceivable, however, that an individual is born with a personality that is a blank slate. The paper quoted above also includes this:

In humans, estimation of heritability has been applied to diseases and behavioural phenotypes (e.g., IQ), and it has helped establish that a substantial proportion of variation in risk for many disorders, like schizophrenia, autism, and attention deficit/hyperactivity disorder, is genetic in origin.

If a tendency towards autism or ADHD has a genetic component, then it seems likely that a tendency towards other, less specific, traits, such as extraversion, must also be to some extent heritable.

Estimating the extent to which a tendency to a personality trait is inherited is fraught with difficulty. Much of the research in this area derives from studies of twins, and in particular the differences between identical and non-identical twins. These studies suggest that the likelihood of personality traits may be as much as 40% to 60% inherited. However researchers taking another approach, looking at differences in DNA and attempting to match them with differences in personality, have arrived at much lower percentages. The most recent research – for instance papers by Eric Turkheimer – attempts to establish a middle ground between the two approaches.

Then there is the question of intelligence. Clever parents seem to have clever kids. But to what extent that is true, let alone to what extent if true it can be ascribed to heredity, is the subject of debate that has raged for decades. There is no agreed definition of intelligence, in the first place. The IQ test as a measure of intelligence is still used by some, even though it has been shown that a high IQ demonstrates only an ability to perform well in IQ tests. Some sort of intelligence is required to achieve academic success, but there seem to be plenty of sharp-minded people without university degrees. To attempt to quantify the heritability of a trait that cannot even be defined seems to me the summit of futility.

But it’s undeniable that there is a high degree of heritability in respect of some conditions that cause cognitive problems and learning difficulties. And therefore it seems to me logical that the reverse is likely to be true: that there is at least some element of heritability when it comes to superior cognitive ability and ease of learning. Clever parents seem to have clever kids.

So this is what it comes down to. Some things about an individual are determined by his or her genetic inheritance – the luck of who the parents were, and the luck of the package of DNA each of them donated when one sperm out of tens of millions fertilised one egg out of hundreds. Quite a lot of things, as it turns out: sex, obviously; physical characteristics in absolute, including skin, hair and eye colour, and others as tendencies, such as height, body shape, facial features; heritable conditions, which include not just physical conditions such as haemophilia and Crohn’s Disease but also disorders such as ADHD; and, to an extent difficult to determine, personality traits and even intelligence. And therefore much of what makes you the person you are is determined at the moment you were conceived.

In these past few instalments I have merely scratched the surface of the subject of heritability. It is a vast field of ongoing research and furious debate. I will leave it there and move on to the luck, or lack of it, that may accrue to an individual after conception.

I hope, though, that you’re already getting angry. Not at me, I hasten to add. I hope you’re getting angry at the people who say things like this:

  • Successful people are not gifted; they just work hard, then succeed on purpose — G K Nielson
  • Self-belief and hard work will always earn you success — Virat Kohli
  • Nothing ever comes to one, that is worth having, except as a result of hard work — Booker T Washington

Hard work as the key to success. ‘Work is the best route out of poverty,’ as Conservative politicians are so fond of saying. Try telling that to someone with multiple sclerosis or Huntington’s Disease; or someone whose mental age will always be that of a child. I have no idea who you are, Virat Kohli, but you should be aware that there are people who can have a mountain of self-belief and who will work every day until their limbs hurt every night and they will never, can never, ‘earn success’.

I will return in a later instalment to discuss the phenomenon of lucky, wealthy, privileged and smug men (yes, it’s usually men) who despite having had an easy life ascribe their wealth and position to their hard work and are always happy to recommend hard work to others less privileged. Yes, I’m talking about you, Rishi Sunak.

Life is a lottery. The advantages and disadvantages possessed by an individual are, primarily, those provided at the moment of conception; these are ameliorated or worsened during pregnancy and childhood, during which time other advantages and disadvantages are loaded on, and those new advantages and disadvantages are in their turn ameliorated or worsened. The eventual adult emerges, shaped entirely by luck.

There is some way to go before we reach the adult. We are, though, ready to move on from the moment of conception, and in the next instalment I will consider what good and bad luck can attach itself to a foetus in the womb.  

The only way to deal with an unfree world is to become so free that your very existence is an act of rebellion.