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.
This social choice around marriage has profound implication in a world of genetic transmission for the overall individual distribution of social abilities in society, and for the rate of social mobility.
The above point is that when parents do the choosing, particularly in arranged marriages where the children are very young, they cannot do the careful matching which free adults can do (when the groom is about 27, the bride about 25) and know something about people and how the world works.
Here is a very blunt finding: if people choose their marital partners very carefully, looking to their underlying genotypical strengths, then differences in social outcomes in society will be preserved and strengthened. There will be little social mobility, and different classes will develop and persist. There will be some rising and falling in the short term, partly caused by noisy measures of status, and some very slow rising, but nothing like the rapid social mobility which people are trying to bring about by compensatory policies. Conversely if this additive genetic formula is wrong, and if environments have strong effects, then there will be a poor match between these genetic predictions and what is actually found in the historical record. There will be no straight-line graphs showing that social outcomes match the degree of genetic relatedness between persons.
Here is the effect of strong marital selection in a picture:
The effect is to have more people in the low range of intelligence, and more people in the high range of intelligence than would be the case if people mated without matching their ability levels. Furthermore, if the next generation persist in choosing their partners carefully, these differences in outcome will be perpetuated and the proportion of very bright people will slowly increase. Do that for 12 centuries and you get the Industrial Revolution.
As the generations go by you start getting more bright people. The problem is, what does one do with them. In purely agrarian societies there are not many opportunities for them, so those bright children competed for limited economic and social resources, the less able and competitive falling downwards, which had the paradoxical effect of “bootstrapping” the rest of the population, as cognitive ability and bourgeois traits rose across all levels of society, leading to higher industriousness and innovativeness.
What we can do now is work our way down the family tree shown above, and see what a purely additive genetic model would predict about people’s social status, assuming a high degree of marital assortment. Long run social mobility rates will depend purely on the degree of genetic assortment in marriage, and the decline in correlations should follow a very regular pattern as we go down through the distant cousins.
This is pretty spooky. Your (alive) cousin and your (dead) great grandfather, who are the same genetic distance from each other, are the same degree of likeness to you in their social status, their higher education and their wealth. That cannot be explained by the usual cultural theories, in which your cousin might conceivably have had some helpful social connection with you. This research finds that social connections seem to be playing almost no role. Indeed, even parents dying when you are young seems to have very minor influence.
Your great grandfather did not live in your household, go to your school, nor get the same pre-school intelligence-boosting exposure to critical race theory. However, because of even distant genetic similarity he is similar to you. Also, to drive the point home, your very dead great, great, great grandfather is just as related to you as a second cousin. (As all of you know, that is the child of one’s parent’s first cousin). Who are these people? Distant as they may be genetically, and non-existent as they may be in the practical terms required by social/cultural theories of social mobility, what emerges from this research is that even at that large genetic distance these very distant relatives are like you to some detectable degree.
As regards siblings, the correlation between parents and any one child will be equal or higher than the correlations between siblings. However, that goes against the popular notion that the family you live in gives all the children the same advantages. On any environmental account of social accounts the correlation between children should be greater than that between parent and child. So this constitutes an interesting test of these competing accounts of social outcomes.
With genetic transmission of social outcomes there should be a strict symmetry of correlations between the paternal and maternal side of the family. The correlation, for example, in any outcome between the paternal grandfather and child should equal that between the maternal grandfather and child. In contrast with social transmission of social outcomes we can imagine significant asymmetry. Property may descend more through the male than the female line, and grandfathers might be more influential in career placement.
As anticipated, the link between paternal wealth is stronger than for maternal wealth, but the effects on social status and education are the same. Mothers matter (genetically).
Another implication of the additive genetic model is that there will be linearity in the regression to the mean observed between generations. The rate of movement to the mean will be the same all across the distribution of parental characteristics. It will be the same for the bottom 1% as for the top 1%. There will thus be no “wealth traps” or “poverty traps” where children of parents at the extremes of the social distribution show unusual persistence in their characteristics, as would potentially appear in social mechanisms of inheritance.
Here is what is found for wealth at death:
In fact, wealth seems to follow the Fisher formula very well, and explains almost all of the variance. All the assorted distant family members fall into place according to their genetic relatedness.
The same is true, though not so sharply, for educational achievement:
This is still very respectable, accounting for two thirds of the variance. The general trend is apparent.
There should be no effects of family size, birth order (though wealth might be an exception), or between living and dead relatives. Living grandparents should predict child outcomes no better than dead relatives. Only the parents genetics matter. The relatives merely provide information on the underlying genotype of the parents, the information they provide depending on their genetic distance from the parents.
So, in the results which follow, if all the different family relationships lie on a straight line, then the simple Fisher additive model is enough to explain the long-term persistence of status, without much if any need for cultural explanations. Wealth should be an exception, since that can actually be transmitted from one generation to another.
For occupational status, the results are almost perfect.
It is highly unusual in the social sciences to have an R2 of 96. This is a straight-line function, with all the disparate extended family members falling very close to the predicted line.
To hammer home the point, and look at a broader range of outcomes, here is a plot of father-son and uncle-nephew correlations.
Again, a very tidy picture, showing that while father-son correlations are expected by the cultural model, that model does not predict that they would be so closely mirrored by the uncle-nephew correlations.
Again, another drumbeat, father-son compared to brother:
This is a very tidy picture.
Here is another, which I will come back to in further posts, which shows the degree to which brides and grooms are matched with each other:
This is a crafty analysis, carried out before universal access to primary education, in which it has been noted whether the bride and groom can sign their names, and the status of the bride (not given in the marriage certificate) can be derived from the occupation of her father.
To summarize, the simple genetic model generates testable predictions, and those are largely supported by the historical records. Cultural models would struggle to explain these patterns detectable in distant relatives who cannot participate in the social conspiracies which are alleged to create unfair outcomes.
It is generally assumed that the elements that define social status – occupational status, educational attainment, wealth, and even health – are transmitted across generations in important ways by the family environment. Above we show that the patterns of correlation of social status attributes in an extended lineage of 402,000 people in England are mainly those that would be predicted by simple additive genetic inheritance of social status in the presence of highly assortative mating around status genetics.
Parent-child correlations for a trait equal those of siblings, and the patterns of correlation of relatives of different degrees of genetic affinity is mainly consistent with that predicted by additive genetics. Further, family size and birth order, elements that would significantly affect the family environment for children, have modest effects on adult outcomes. The underlying persistence of traits is such that people who have likely never interacted socially, such as second to fifth cousins, remain surprisingly strongly correlated in terms of occupational status and wealth. The patterns observed imply that marital sorting must be strong in terms of the underlying genetics. If this interpretation is correct then aspirations that by appropriate social design, rates of social mobility can be substantially increased will prove futile. We have to be resigned to living in a world where social outcomes are substantially determined at birth.
Personally I would argue that this should push us towards compressing characteristics. The Nordic model of the good society looks a lot more attractive than the Texan one.
Using an elegant and extremely detailed method, Greg Clark has made a strong case for genetics making a big difference in all the things which agitate us in politics: status, social mobility, earnings and wealth. His conclusion that “We have to be resigned to living in a world where social outcomes are substantially determined at birth” is a profound one. It goes totally against the standard discourse of politics. It will not be popular. It contains a hostage to fortune, which is that marital choices must be made carefully, but must have issue. Careful matches must result in children or societies will not continue to rise.
Greg goes on to add a personal preference that compensation should be made on the Nordic model, but others may not be that charitable, or prudent. This discussion paper needs discussion, so I welcome your comments.