I do not wish to accuse my readers of being economists, sociologists or anthropologists, but I am willing to bet that some of you think that the way your parents brought you up, and the schools and community you were raised in, had a big influence on your later achievements in life.
A reasonable belief, but probably a mistaken one.
In fact, it is likely that all that matters is who your parents were, by which I mean your blood parents. Furthermore, conceiving you was the big step, and the rest was due to your being kept alive, and little more.
Here is a discussion paper, written for a conference-attending professional audience, which gives a technical account of the preliminary results of a large study still in progress. I will concentrate on some of the main points, and will leave discussion of some other matters (like assortative mating) to another later post.
For Whom the Bell Curve Tolls: A Lineage of 400,000 English Individuals 1750-2020 shows Genetics Determines most Social Outcomes
Gregory Clark, University of California, Davis and LSE (March 1, 2021)
Economics, Sociology, and Anthropology are dominated by the belief that social outcomes depend mainly on parental investment and community socialization. Using a lineage of 402,000 English people 1750-2020 we test whether such mechanisms better predict outcomes than a simple additive genetics model. The genetics model predicts better in all cases except for the transmission of wealth. The high persistence of status over multiple generations, however, would require in a genetic mechanism strong genetic assortative in mating. This has been until recently believed impossible. There is however, also strong evidence consistent with just such sorting, all the way from 1837 to 2020. Thus the outcomes here are actually the product of an interesting genetics-culture combination.
Greg Clark says:
It is widely believed that while social status – measured as occupational status, income, health, or wealth – is correlated between parents and children, this correlation is driven by parental investments in children, or by cultural transmission. This belief has profound influence on peoples’ perception of the fairness of social rewards, of the need for government intervention in the lives of disadvantaged children, and of the social value of education. In this paper I test whether culture/human capital or genetics offers a better explanation of the inheritance of social attributes, using a lineage of 402,000 English individuals 1750-2020. To do so we have to specify both a general model of cultural/human capital inheritance, and one of genetic inheritance. There is already a well established model of additive genetic inheritance, formulated by Fisher in 1918. This I test against the data below. Specifying a model of cultural/human capital transmission as an alternative is more difficult. The ways culture/human capital has been hypothesized to operate are many and varied.
So, Clark offers us a straight fight between a simple genetic formula and the more amorphous, all-encompassing but vague cultural explanations.
The genetic formula was proposed by Fisher, but since putting a formula in the text cuts readership in half I will eschew it, and instead describe it in plain English: most complex human traits are influenced genetically by the additive effect of many locations in the DNA where there are variants in the base pairs (none, one, or two positive variants), where each location itself has a very small effect on the trait in question. So, you just add up all those small effects to get a total score for the trait in question, which is the additive inheritance. That’s it.
For example, Galton noticed that parent’s height was passed on to their children, though the precise mechanism was not known. The long run intergenerational correlation should be close to 0.5.
Now we would calculate height accurately with polygenic risk scores, but that is not essential. With the additive model you don’t have to worry about fancy stuff like dominant or recessive genes, or interactions between different genes at different locations. This is a very simple and clear model of the intergenerational transmission of social status. In this model, you don’t even have to worry about the environment. Genetics is all you need in order to predict your achievements in life.
When we come to social outcomes the idea here will be that people inherit a set of abilities that determine, whatever their parents’ circumstances, their ultimate outcome in terms of occupational status, education, health or longevity. For wealth, where there is an actual transfer between generations, we would not expect the Fisher rules to hold.
Now a tiny bit of jargon. Each parent transmits their genes, plus a random element. You get exactly 50% from each parent (except the sex genes) but the 50% you get from your father (or mother) are slightly random samples of his genes. Your brother gets a different sample. That is why siblings are similar, but uniquely slightly different. So, what you see in each person is the (phenotype) which is their ancestry (genotype) plus the slightly random assortment they got from their parents. On average, mothers will contribute as much as fathers, so if the genetic theory is correct, mothers will contribute as much to the status of their children as do fathers. (Probably not what the cultural view would predict).
It seem very likely that people choose each other by carefully getting to know their partners (the phenotype), and in that way they will also pick out their partner’s underlying family qualities (the genotype).
The simple genotypic model allows you to work out the degree of relatedness of all your relatives, as shown below. As you get further away from yourself the correlations will go down in a lawful way caused by the genetic totals.
This little chart is very interesting, in that it allows the testing of genetic links in various ways. Your correlation with your cousin is the same as your correlation with your great-grandparent whom you probably haven’t ever met. So, on the Fisher equation, finding out about the achievements of a dead great-grandparent should tell you as much about your eventual social status as your still-alive cousin, even though the latter might have helped you with a job offer. On the cultural model, a cousin will have more potential influence on you than a dead great-grandparent.
We can see if the simple genotype model explains the obtained data.
Clark says, about assortative mating, or marital selection (marriage partners choosing who they marry) which he labels “m”:
There is no intrinsic reason that people should match in marriage based on their social abilities. They could match purely on physical characteristics, or on personality traits unrelated to social and economic outcomes. They do match, in some societies, on whatever cousins are available of the appropriate age and gender. Interestingly, though, if matching is just to a random cousin then in equilibrium in such a society “m” will be quite low at around 0.23, whereas in England the evidence for “m”, as mentioned, is in the order of 0.6-0.8.