Editor’s note: This article was adapted from Robert Plomin’s new book Blueprint: How DNA Makes Us Who We Are. For a review of Blueprint by Gregory Cochran, see here. For a piece by Toby Young on the book, and a wider discussion of social genomics and why it attracts the hostility of some academics, see here.

If schools, parenting and our life experiences do not change who we are, what does this mean for society, especially for equality of opportunity and meritocracy? In particular, does it mean that the genetically rich will get richer and the poor poorer? Are genetic castes inevitable? What does this say about inequality?

These questions have been bound up in the topic of meritocracy, which is not the same thing as equal opportunity. Equal opportunity means that people are treated similarly, for example, everyone is given equal access to educational resources. Meritocracy only comes in when there is selection, for example, for education and employment. Meritocracy means that selection is based on capability and competence rather than unfair criteria such as wealth, prejudice or arbitrariness.

Although meritocracy sounds like an irresistibly good idea, both parts of the neologism “meritocracy” are loaded with unpalatable connotations. The noun “merit” refers to ability and effort but it also connotes value and worth. It is derived from the Latin word meritum meaning “worthy of praise.” The “—ocracy” part of “meritocracy” refers to power and governance. Putting these two components of meritocracy together with genetics implies that we are governed by a genetic elite whose status is justified by their ability and effort. Instead, it could be argued that people who got lucky by drawing a good genetic hand do not merit anything. Their luck at learning easily and getting satisfying jobs is its own reward. And who says we should be governed by genetic elites? The populist strain of politics around the world suggests a desire for the opposite.

Three Findings from Genetic Research

Three of the main findings from genetic research transform how we think about equality of opportunity and meritocracy. These findings are about heritability, non-shared environment and the nature of nurture. In summary, genetics provides most of the systematic variation between us, environmental effects are random, and our chosen environments show genetic influence. These findings have different implications for equal opportunity and meritocracy.

At first glance, genetics seems antithetical to equality of opportunity, violating the principle enshrined in the second sentence of the 1776 United States Declaration of Independence that all people are created equal. However, the American founders did not mean that all people are created identical. They were referring to “unalienable rights,” which include “life, liberty and the pursuit of happiness.” In less lofty terms, this means equal protection before the law and equal opportunity. But equal does not mean identical. If everyone were identical, there would be no need to worry about equal rights or equal opportunity. The essence of democracy is that people are treated fairly despite their differences.

The most important point about equality of opportunity from a genetic perspective is that equality of opportunity does not translate to equality of outcome. If educational opportunities were the same for all children, would their outcomes be the same in terms of school achievement? The answer is clearly ‘no’ because even if environmental differences were eliminated genetic differences would remain.

What follows from this point is one of the most extraordinary implications of genetics. Instead of genetics being antithetical to equal opportunity, heritability of outcomes can be seen as an index of equality of opportunity. Equal opportunity means that environmental advantages and disadvantages such as privilege and prejudice have little effect on outcomes. Individual differences in outcomes that remain after systematic environmental biases are diminished are to a greater extent due to genetic differences. In this way, greater educational equality of opportunity results in greater heritability of school achievement. The higher the heritability of school achievement, the less the impact of environmental advantages and disadvantages. If nothing but environmental differences were important, heritability would be zero. Finding that heritability of school achievement is higher than for most traits — about 60 percent in Western countries — suggests that there is substantial equality of opportunity.

Environmental differences account for the remaining 40 percent of the variance. Does this imply inequality of opportunity? To the extent that environmental influences are non‐shared, this means that they are not caused by systematic inequalities of opportunity. However, genetic research on primary and secondary school achievement is an exception to the rule that environmental influences are non‐shared. For school achievement, half of the environmental influence — 20 percent of the total variance — is shared by children attending the same school. This finding implies that up to 20 percent of the variance in school achievement could be due to inequalities in school or home environments, although this effect mostly washes out by the time children go to university.

The third finding, about the nature of nurture, is also relevant to understanding the relationship between equal opportunity and outcomes. What look like systematic environmental effects in fact reflect genetic differences. For example, the socioeconomic status of parents is correlated with their children’s educational and occupational outcomes. This correlation has been interpreted as if it is caused environmentally. That is, better‐educated, wealthier parents are assumed to pass on privilege, creating environmentally driven inequality in educational opportunity and stifling what is called intergenerational educational mobility.

Genetics turns the interpretation of this correlation upside down. Socioeconomic status of parents is a measure of their educational and occupational outcomes, which are both substantially heritable. This means that the correlation between parents’ socioeconomic status and their children’s outcomes is actually about parent–offspring resemblance in education and occupation. Phrased as “parent-offspring resemblance,” it should come as no surprise that genetics largely mediates the correlation. Parent-offspring resemblance is an index of heritability, and heritability is an index of equal opportunity. So, parent-offspring resemblance for education and occupation indicates social mobility rather than social inertia.

Gene-Environment Correlations

A more subtle way to think about the nature of nurture and its relationship to equality of opportunity is gene-environment correlation, which means that our experiences are correlated with our genetic propensities. Genetic differences in personality, psychopathology and cognitive ability make us experience life differently, as we saw in relation to the nature-of-nurture phenomenon. In relation to education, more highly educated parents provide both nature and nurture that work together to affect their children’s chances to do well at school, for example, in reading and their general attitude to education. Schools select children into streams on the basis of heritable traits such as ability and previous achievement. These are examples of what behavioral geneticists call passive and reactive gene-environment correlation, respectively.

The most important type is active gene-environment correlation. Children actively select, modify and create environments correlated with their genetic propensities. For example, genetic differences in children’s aptitudes and appetites affect the extent to which they take advantage of educational opportunities. This is why equal opportunities cannot be imposed on children to create equal outcomes. Genetic differences in aptitudes and appetites influence the extent to which children take advantage of opportunities. To a large extent, opportunities are taken, not given.

It would be a mistake to see gene-environment correlation as inequality, because it is, ultimately, based on genetics. For this reason, gene-environment correlation is difficult to disrupt. We can’t stop parents from providing correlated nature and nurture to their children unless we adopt children away at birth. We could outlaw selection in schools, but in the classroom it is impossible as well as undesirable for teachers to treat children the same, regardless of their genetic differences. Finally, trying to stop children from actively seeking experiences correlated with their genetic appetites and abilities is futile.

What this means is that high heritability of school achievement indicates that educational opportunities are substantially equal. Attempts to increase equality of opportunity should focus on reducing shared environmental influence, although shared environment at most accounts for 20 percent of the variance in school achievement. Non-shared environmental influences are out of reach because they are unsystematic and we don’t know what they are. Correlations between opportunity and outcome are genetically driven. This is another way in which DNA makes us who we are.

It is worth reiterating that this genetic research describes the mix of genetic and environmental influences on individual differences in school achievement in specific samples at specific times. Most of the research comes from developed countries, especially Europe and the US, in the 20th century. The results could be different for different countries in different times. Our focus here is on the effects of equal opportunity on individual differences in school achievement. As access to education broadens, heritability would be expected to increase. The first twin study on this topic found that heritability of educational attainment increased and the impact of shared environment decreased in Norway following WWII, when access to education expanded. Subsequent studies in several countries also found increased heritability and decreased shared environmental influence after WWII, as equality of educational opportunity increased. Some recent evidence suggests this might be going in reverse in the US in the 21st century, with decreased heritability and increased shared environmental influence on educational attainment, which suggests there is greater inequality of educational opportunity.

School Selection

In contrast to equal opportunity, the concept of meritocracy is relevant only when there is selection, for example, selecting children into certain schools. At the level of primary school in the UK there is little selection because most parents send their children to a local school. Equal opportunity in this case means that children at different schools receive equally good education.

Selection becomes more of an issue at the level of secondary school. Students vie to get into the “best” secondary schools, which leads to selection. The issue of meritocracy is about the extent to which selection is based on ‘merit’—in this case, on the students’ ability, prior achievement and other predictors of success.

In the UK the biggest average difference in student achievement is between state-funded non‐selective schools, or comprehensive schools, and selective schools, which include state-funded grammar schools and privately funded schools. The average GCSE scores for children in selective schools, whether grammar or private, are a whole grade higher than for children in non-selective schools.

This average difference in achievement between selective and non-selective schools has been assumed to be caused environmentally—selective schools are assumed to provide better schooling. However, genetic research shows that this difference cannot be credited to better education in selective schools. By definition, selective schools select the most competitive students, choosing meritocratically on the basis of students’ prior achievement and ability and, less meritocratically, on family wealth. For example, at the top secondary schools students are interviewed and tested for several years before they are admitted. In addition, parents and students select the “best” secondary schools in part on the basis of these same factors. That is, if students have not performed well on tests of school achievement in primary school, they are not likely to aspire to high‐flying secondary schools.

So it should come as no surprise that students in selective schools perform better than students in non-selective schools, because it is a self-fulfilling prophecy that the students selected by selective schools for their school achievement do better in their exams at 16, known in England as GCSEs. When we control for the factors that are used to select students the average difference in GCSE scores is negligible and overall GCSE variance explained by school type shrinks to less than one per cent. In other words, selective schools do not improve students’ achievement once we take into account the fact that these schools preselect students with the best chance of success.

This is another example of gene-environment correlation, in that students select schools and are selected by a school in part on the basis of the students’ prior school achievement and ability, which are highly heritable. This explains what would otherwise appear to be an odd result: Students in selective and non-selective schools differ in their DNA. Because the traits used to select students are highly heritable, selection of students for these traits means that students are unintentionally selected genetically.

If better achievement by students in selective schools than by those in non‐selective schools were due to value added by selective schools, this would imply inequality of educational opportunity. But because the difference in achievement disappears after controlling for selection factors, we can conclude that selection is meritocratic. For this same reason, differences in GCSE results for selective and non-selective schools are not an index of the quality of education the schools provide. An attempt to create a fairer comparison was implemented in England in 2017 by correcting GCSE scores at the end of secondary school for achievement at the end of primary school at the age of eleven. This innovation was sold as an index of the value added by schools, which is called ‘progress’. However, we have found that this measure of ‘progress’ is still substantially heritable (40 percent), which means that it is not a pure index of students’ “progress” or schools’ added value. How is it possible that this measure of “progress” is so heritable? The answer is that correcting for school achievement at the age of eleven does not correct for other heritable contributions to performance on the GCSE test such as intelligence, personality and mental health.

Private Schools

Even though schools have little effect on individual differences in school achievement, some parents will still decide to pay huge amounts of money to send their children to private schools in order to give their children whatever slight advantage such schools provide. Even for state-supported selective grammar schools, some parents who can afford to do so will pay a premium to move house to be within the catchment of a better school. I hope it will help parents who cannot afford to pay for private schooling or move house to know that it doesn’t make much of a difference in children’s school achievement. Expensive schooling cannot survive a cost-benefit analysis on the basis of school achievement itself.

There may be benefits of grammar and private schools in terms of other outcomes, such as better prospects for university, making connections that lead to job opportunities later in life, and imbuing students with greater confidence and leadership skills. For example, although only seven percent of students in the UK attend private schools, their alumni notoriously dominate the top professions—over a third of MPs, over half of senior medical consultants, over two-thirds of high court judges and many top journalists.

But are these advantages merely another example of the self-fulfilling prophecy of selecting the best students in the first place? In the case of the difference in GCSE scores between selective and non-selective secondary schools, we have seen that the difference disappears after controlling for factors used in selection. We have found similar results for university prospects. That is, students from selective secondary schools are much more likely to be accepted by the best universities, but this benefit largely disappears after controlling for selection factors. In other words, the students would have been as likely to be accepted by the best universities if they had not gone to a selective secondary school. Indeed, changes in selection criteria for the best universities actually favor a student who does well at a comprehensive secondary school.

It seems likely that the other potential advantages of selective schooling—such as occupational status, income and personal characteristics—are also self-fulfilling prophecies rather than value added by selective schools. Finally, it should be emphasized that if all secondary schools were equally good, there would be no need to select students in the first place. If there were no selection, there would also be a lot less stress for students and their parents. In addition, neighborhood schools foster social integration and a sense of community.

Occupational Status and Income

We have used education as an example of the links between opportunities, capabilities and outcomes, but the same issues apply to occupational status and income. Here, as long as getting a high-status job and making lots of money are priorities, selection is necessary, which raises the issue of the criteria used for selection. As in the example of the over-representation of private schooling among MPs, medical consultants and high court judges, is selection for occupational status and income based on advantage or ability?

Both occupational status and income are substantially heritable, about 40 per cent in more than a dozen twin studies in developed countries. This should not be surprising, because occupational status and income are related to educational attainment and intelligence, which are heritable traits. Similar to the argument we made for education, heritability is an index of meritocratic selection for occupational status and income, so we can conclude on the basis of substantial heritability that selection is considerably meritocratic. Unlike education, shared environmental influence for occupational status is negligible, which means that environmental influences are random and that most of the systematic effects on occupational status and income can be attributed to genetics.

Anyone who has interviewed candidates for a job knows the complexity and capriciousness of selection. In the first place, you can only select from people who applied for the position. In addition, interviews are notoriously poor predictors of performance. These and many other unsystematic factors, including chance, contribute to individual differences in occupational status and income. These factors are not meritocratic, but they do not represent systematic bias.

The nature-or-nurture issue is also relevant for occupations. What look like systematic environmental effects are reflections of genetic effects. An important example is the similarity between parents and their offspring in occupational status and income. As examined earlier in relation to education, parent-offspring resemblance for occupational status and income cannot be assumed to arise from environmental advantages passed on from parent to child. The correlation is chiefly caused genetically, which indicates that the systematic effects of selection, including self-selection, are substantially meritocratic. The same is probably true for the ostensible effect of private schooling on occupational success, as noted earlier.

I would argue that anything that increases the heritability of occupational status and income makes the selection process more meritocratic. The absence of shared environmental influence implies that there are few systematic environmental inequities in the population as a whole, which means that environmental levers for change are not within our grasp. Inherited wealth, which is the epitome of inequity, can be changed, for example, by taxing wealth rather than income. However, inherited wealth is not much related to occupational status or to income, at least as income is currently defined by tax authorities. So, tackling inherited wealth will not make much difference in occupational status or income per se. One thing that would make a difference is to make selection processes more effective in predicting performance, because this would reduce unsystematic influences on occupational status and income. The DNA revolution will transform the selection process by introducing the most systematic and objective predictor of performance by far: inherited DNA differences.

A Genetic Caste System?

At first thought, it might seem that, given free rein, genetics will limit social mobility and calcify society into genetic castes, as happened in India, where for thousands of years mating was limited to members of the same caste. I would argue that this is not a problem in modern societies for two reasons. The first is simple: a lot of the environmental variation between us is not systematic. Random effects will not create stable castes.

The second reason is that parents and offspring are only 50 percent similar genetically. Their genetic similarity means that, on average, brighter parents have brighter children. But their 50 percent genetic dissimilarity means that children of brighter parents will show a wide range of ability, including some children of lower-than-average ability. If you take pairs of individuals randomly, their average difference will be 17 IQ points. First-degree relatives—parents and their offspring or siblings—differ by 13 IQ points on average. This allows plenty of room to go down as well as up the ladder.

In addition, children of high-IQ parents will on average have lower IQ scores than their parents for the same reason that tall parents have taller-than-average children but those children are less tall than they are. For the same reason, most prodigies do not have prodigy parents. This is a statistical phenomenon, not a specific genetic process. That is, the same phenomenon would occur if individual differences were due to systematic environmental factors indexed as shared environment. However, genetics, not shared environment, is the systematic source of individual differences, and it is genetics that leads to concerns about castes.

If children were genetically unrelated to their high-IQ parents, as is the case for adopted children and their adoptive parents, the children’s mean IQ would be expected to be 100, if the adopted children were representative of the population. Because children are 50 percent similar genetically to their parents, genetics predicts that the children’s average IQ will regress halfway from their parents’ IQ to the population average. For example, parents with an average IQ of 130 are expected to have children whose average IQ is 115, regressing halfway back to the population average of 100. This reshuffling of DNA differences in the genetic lottery prevents the evolution of a rigid genetic caste system.

The flip side of this argument is that parents of average ability also have children with a wide range of ability, including children of high ability. Because there are many more parents of average ability than of high ability, this guarantees that most of the individuals of highest ability in the next generation will come from parents of average ability, not from the most able parents. As long as downward social mobility as well as upward social mobility occurs, we do not need to fear that genetics will lead to a rigid caste system.

Fatalism and the Status Quo

Even though most of the systematic differences between people are genetic in origin, this does not mean that we need to be fatalistic and accept the status quo. One reason is that genetics describes what is—it does not predict what could be. You can beat the genetic odds. But it is not fatalistic to recognize that DNA matters and to appreciate genetic differences between our children and between ourselves. It seems only sane to suggest that, when you can, try to go with the grain of genetics rather than fight against it.

A second way to avoid fatalism is to deny the value system that drives the debate about meritocracy and social mobility. It assumes that the point of education is to get better test scores in order to get a better occupation and that the point of an occupation is to achieve high status and make lots of money. Another way of looking at education is as a time to learn basic skills and to learn how to learn and to enjoy learning. It is a decade of their lives when children can find out what they like to do and what they are good at doing, where they can find their genetic selves, which may not dispose them towards higher education. Everyone should be given the chance to learn at school, but not everyone will choose (or can afford) to go on to university.

Similarly, with occupations, where selection cannot be avoided, we will end up with a lot of frustrated people if we only value high-status occupations. Society needs people who are good care workers, nurses, plumbers, janitors, policemen, mechanics and public servants. What I want most for my children is that they are happy and that they are good people. It would be a terrific bonus if they like what they do.

Self-selection is an important factor to the extent that people are free to choose what they do to earn a living. Self-selection involves listening to genetic whispers, not just about intelligence but also about personality and interests. These options include choosing a job that just pays the bills rather than a high‐income occupation that might come with a high‐stress price tag, or an especially enjoyable vocation that might not pay the bills. Beyond the money needed to get by, letting money define success in life does not achieve happiness, enjoyment or goodness. In a just society, jobs that require less “merit” would nonetheless be rewarded monetarily so that they provide a reasonable standard of living.

We could also deny the value system based on money at a more political level. Much of the concern about inequality and social mobility is about income inequality. Individual differences in income are, like everything else, substantially heritable, about 40 percent. Income correlates with intelligence, and genetics drives this correlation. But this does not mean that higher intelligence merits more income. I would argue that genetic wealth is its own reward. If society really wanted to reduce income inequality, it could do so directly and immediately with a tax system that redistributes wealth.

A Just Society

My value system suggests that we need to replace meritocracy with a just society. Although rigid genetic castes will not come into being, social mobility creates genetic inequality, which leads to an inherent inequality of opportunity. That is, children dealt a lucky genetic hand have a better chance of doing well at school and getting a better job and making more money. This inequality in outcome is not going to be tackled indirectly through the educational system. As mentioned, if all children were taught exactly the same, their genetic differences would still lead to differences in their achievement, which would lead to differences in occupational outcomes. Again, economic inequality could be dealt with directly through a redistributive tax system that reduces the gap between rich and poor.

I think people are more concerned with fairness and a just society than with economic inequality per se. It seems unfair that 60 percent of the increase in US national income in the last three decades went to just the top one per cent of earners, primarily due to soaring salaries at the top end of the pay scale. However, I would argue that more important than the relative inequality of income for this top one per cent is the absolute inequality of the bottom third, whose debts exceed their assets.

Equality of opportunity, income inequality and social mobility are some of the most critical issues in society today. They are hugely complicated topics that heavily depend on values. My objective has been to look at these issues through the single lens of genetics, to show how DNA makes us who we are. However, no specific policies necessarily follow from genetic findings, because policies depend on values. My values, not my science, lead me away from meritocracy towards a just society.

Robert Plomin is a professor of behavioral genetics at King’s College London.

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