The Lottery Of Life

Fifth instalment - the shuffle and the deal

The shuffle and the deal – the moment of conception

In the previous instalment I explained that some pretty basic elements of a person’s good or bad luck are determined before the person is so much as conceived: factors such as the health and nutrition of the parents, and even of the grandparents, of the person yet to be conceived have a surprisingly large influence on his or her physical and mental state. Much about you was decided before your parents even met.

In this instalment we arrive at the moment of conception: the meeting of sperm and egg; the combining of twenty-three chromosomes carrying a random selection of the father’s DNA with twenty-three chromosomes carrying a random selection of the mother’s to create a zygote – an embryonic new person.

It seems to me that this moment of creation – this thing that brings you into potential existence, this event that happens to you before you’re even you, before you’re even an undifferentiated clump of cells – this shapes you far, far more than any other factor that affects you either before or after conception. These things are impossible to quantify, but I would not be surprised if the mixture of 20,000 genes that constitutes the physical and mental blueprint for a person determines more about that person than all other factors taken together.

It’s time for a confession: I’m not a geneticist. I know no more about this subject than the next reasonably well-informed layman. My reading around human genetics leads me to understand that among geneticists there is debate about what physical and psychological traits can be ascribed to a person’s DNA and, when such ascription can be made, the extent to which DNA is solely responsible.

There is also the question of epigenetics – a term that is used in various contexts but which often refers to the interaction between the genetic code carried in a person’s DNA and the environment that surrounds a cell, or a group of cells, or the whole person. It’s a minefield for the academics and scientists working in this area, and I’m not remotely qualified to comment.

One thing I do know, though – and here I’m straying into territory that I map in one of my other blogs, English As She Is Writ – is that the words epigenetics means ‘above or around genetics’, because ‘epi’ is a Greek-origin prefix meaning over or above. For instance the epidermis is the top layer of skin. And the epicentre of an earthquake is the place on the surface of the planet that is above the subterranean location of the actual quake. The epicentre is not the centre; it’s above the centre. So please, all of you – and in particular journalists and commentators who should know better – can we have no more of ‘all of France is in uproar, but Paris is the epicentre of the rioting’. In that example Paris isn’t the epicentre; it’s just the centre. If you don’t know what a word means, don’t use it.

Having got that off my chest, I’ll return to genetics, and the question of heritability – the extent to which physiological and mental traits (one’s phenotype) are determined by one’s genotype.

Fortunately I am able to avoid having to take a position on the vexed issue of nature versus nurture: as I’ll discuss in future instalments, my argument is that a person’s inherited traits and his or her environment both contribute to his or her luck in the lottery of life.

It is clear, however, that there are traits that are determined almost entirely by genetics – that are highly heritable; others that are more or less influenced by one’s unique (other than in the case of identical twins) admixture of DNA; and yet others – for instance the language that one learns to speak – that have nothing to do with one’s genes.

Height, for instance, is mainly heritable. A 2001 paper in the International Journal of Obesity and Related Metabolic Disorders found that height ‘has a heritability of 89% in the United States. In Nigeria, however, where people experience a more variable access to good nutrition and health care, height has a heritability of 62%’.

Steven Pinker in his 2002 book The Blank Slate: The Modern Denial of Human Nature, makes the following point:

Concrete behavioral traits that patently depend on content provided by the home or culture—which language one speaks, which religion one practices, which political party one supports—are not heritable at all. But traits that reflect the underlying talents and temperaments—how proficient with language a person is, how religious, how liberal or conservative—are partially heritable.

It seems to me that some traits – to do with physical appearance, for instance, and specific heritable diseases – are clearly determined entirely or largely by one’s genes; whereas with other traits – those to do with a person’s personality, attitudes, preferences – there is likely to be a genetic component but establishing a specific percentage of genetic contribution is difficult and indeed may be a futile quest, given that such traits are likely to result from the interaction of genetics and environment.

To abandon for a moment the metaphor of life as a lottery, and replace it with the jeu d’esprit of life as a game of five-card draw poker, it is reasonable to view the five cards that one is initially dealt as corresponding to the determinants – the health and nutrition of one’s parents, the genotype provided by one’s parent – that are with you from conception. One’s environment and upbringing allow one or two of those cards to be changed. But to a large extent the resources you have – the person you are, your appearance, abilities, disabilities, personality – were fixed before you were even a foetus.

In the next instalment I’ll look at some of the highly heritable traits and discuss how they affect a person’s luck in life.  

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