The Lottery Of Life

Fourteenth instalment - gene-environment interplay

I was born in a crossfire hurricane
And I howled at the morning drivin’ rain
I was raised by a toothless, bearded hag
I was schooled with a strap right across my back
Selected lyrics from Jumpin’ Jack Flash by the Rolling Stones

Poor old Jack Flash seems to have had a very unlucky start in life. And yet in the chorus of the song he insists that not only is it all right now, but it is in fact a gas.

All of which serves to introduce the subject of the environmental factors that – if we imagine a new-born person as a work of art – paint the fine detail on to the canvas whose subject matter, underlying outline drawing, colour palette and stand-out features have already been determined (see previous instalments).

Before I embark on attempting to itemise such environmental factors, I’d like to draw attention to two papers that can be found on the internet which together provide insight into how to assess environmental factors.

The first is a paper published in Social Science Research, Volume 77, January 2019, entitled Scholarly culture: How books in adolescence enhance adult literacy, numeracy and technology skills in 31 societies by Joanna Sikora, M.D.R. Evans and Jonathan Kelley. It can be found here:

The paper was the subject of an article in the Guardian, which can be found here:

The Guardian article summarises the paper’s conclusion thus:

According to the paper, teenagers with only lower levels of secondary education, but who came from a home filled with books, “become as literate, numerate and technologically apt in adulthood as university graduates who grew up with only a few books”.

This appears to be all the evidence we need of an environmental factor at work. A child – specifically a teenager- growing up in a house full of books will become, all other things being equal, more literate and numerate than a teenager with the same level of education growing up in a house without books. It seems obvious. And it seems to be all nurture and no nature: all environment and no genetics.

The paper on Social Science Research prompted a paper in response. It was published in January 2021 in NPJ Science of Learning volume 6, entitled Nurture might be nature: cautionary tales and proposed solutions by Sara A. Hart, Callie Little and Elsje van Bergen. It can be found here:

The paper points out that many factors affecting development that appear to be entirely environmental have a genetic component. The authors warn against ignoring possible genetic factors and provide a flow-chart to assist in assessing the genetic element of any such environmental factor. In the particular case of the availability or otherwise to teenagers of books, they say this:

Parents share genes related to reading ability with their children, and also control the number of books in their home. This creates gene–environment interplay. It is important to note that the environmental effect may still have a causal role, even with gene–environment interplay. If genes play a role but are not modelled, the correlation between the environmental measure and the child’s trait is genetically confounded.

 In other words, the presence of books in a teenager’s environment will have two genetic components: the parents’ inherent reading ability (if they are keen readers the house will have more books); and the teenager’s own inherent reading ability – which he or she will have inherited from his or her parents – which will also affect the number of books in the house.

In sum, it may well be the case that being surrounded by books increases literacy; but the fact that there are many books in the house will be determined to some extent by genetic factors – the extent to which the parents’ and the teenager’s DNA inheritance makes them interested in reading. 

It might be argued – entirely reasonably – that a household’s relative wealth or poverty will have an effect on the number of books it contains. It might be argued that this might well be the single most significant factor. I wouldn’t disagree, and I think the authors of the Nurture might be nature paper would also not disagree. My understanding of their conclusion is that there is gene-environment interplay as well as, not instead of, purely environmental factors. I would merely point out, to use the most basic example of an environmental factor, that whether one is brought up in a wealthy household or a poor household is just another element of one’s luck in life. An infant has no control over the surroundings in which he or she is brought up.

I’ve spent some time on this because it’s important to understand that the environment in which a person grows from baby to teenager affects that person’s development and is therefore a factor in that person’s good or bad luck: those sixteen or eighteen years – particularly the first few of them – deal a few more cards to complete the hand that the person holds.

However the environment is not a thing separate from genetics. The process by which genetics affects the number of books in the household (the parents’ reading ability and interest; the child’s reading ability and interest as inherited from the parents) applies to many other aspects of the child’s environment. We have already seen, for instance, that being female or dark-skinned is relatively unlucky; sex and skin colour are factors determined entirely by genetics. A child brought up by a single mother or dark-skinned parents is, on average, more likely to be brought up in a relatively poor household. Poverty, like wealth, is handed down from generation to generation.

In the next instalment I’ll concentrate on wealth and poverty, and the good and bad luck they dispense to the young individual.

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