It is a commonplace of school reunions that ex-pupils make a furtive reckoning as to which of them has Done Well. Comparisons are odious, but all too human. How has it gone for you? Naturally, the actuarial odds are against personal success, since success, by definition, must be that which stands out from the crowd, and accrues to only a minority. 1 in 100 may be the first foothills of note, 1 in 1000 a greater peak more worthy of attention, but for eminence only those at the highest peak of 1 in 10,000 qualify for eminence. That was the requirement Galton set, but he no longer exists, so my reference to him is void for lack of meaning.
Looking at your peer group gives you a cross-sectional comparison, but for a longitudinal one a natural first step is to compare your personal achievements with those of your parents. A one generational change is within the span of apprehension, and has some emotional bite to it. It is probably best to set age 40 or thereabouts as the career midpoint for inter-generational comparisons. Have you risen or fallen? Some intrepid researchers have dared to find out what causes these differences.
The Contribution of Cognitive and Noncognitive Skills to Intergenerational Social Mobility.
Matt McGue, Emily A. Willoughby, Aldo Rustichini, Wendy Johnson, William G. Iacono, and James J. Lee
First Published June 30, 2020 Research Article
We investigated intergenerational educational and occupational mobility in a sample of 2,594 adult offspring and 2,530 of their parents. Participants completed assessments of general cognitive ability and five noncognitive factors related to social achievement; 88% were also genotyped, allowing computation of educational-attainment polygenic scores. Most offspring were socially mobile. Offspring who scored at least 1 standard deviation higher than their parents on both cognitive and noncognitive measures rarely moved down and frequently moved up. Polygenic scores were also associated with social mobility. Inheritance of a favorable subset of parent alleles was associated with moving up, and inheritance of an unfavorable subset was associated with moving down. Parents’ education did not moderate the association of offspring’s skill with mobility, suggesting that low-skilled offspring from advantaged homes were not protected from downward mobility. These data suggest that cognitive and noncognitive skills as well as genetic factors contribute to the reordering of social standing that takes place across generations.
The authors adroitly encapsulate the dilemma of social mobility studies:
A major challenge to a belief in meritocratic processes is that advantaged parents are much more likely to have advantaged children than are less advantaged parents (Cullen, 2003). Wealth, social capital, and involvement are all ways in which parents can create opportunities for their children that are not widely available to others (Breen & Goldthorpe, 2001). Yet unequal opportunity is not the only factor contributing to the intergenerational transmission of inequality. High-achieving parents also transmit to their children, genetically and environmentally, the skills that contributed to their own success (Swift, 2004).
Cognitive ability was assessed at 17 years of age and on the Wechsler which is excellent; occupational status in late 20s, which the authors admit is too soon (yet it favours the environmental rather than the genetic hypothesis, since parental contributions of money and contacts will be immediate, whereas any genetic contribution will take time to accumulate).
Incidentally, there is a slight problem with studying intergenerational status, which is that some of the measures change (they are not invariant). Formerly, few students went to college, and now a majority do. This alters the meaning of higher education measures, as the authors explain. I have concentrated on occupational level, which is less subject to those problems.
However, the main point of this paper is to study families, and to compare siblings within families. If wealth is the engine which provides children with good jobs, then all wealthy progeny will rise, and children of poor families will languish. This study uses families as their own controls, and looks at what sibling heterogeneity may contribute to life outcomes.
Gloriously, the authors cite Nettle (2003) and use his method of regressing each predictor variable on offspring–parent difference in attainment, parent level of attainment, and their interaction, separately for education and occupation. He made a good contribution to the debate and his paper should be known more widely.
Polygenic scores for intelligence are not yet good enough to explain a major part of intelligence, but one can at least check whether the equations point in the right direction. The authors say:
As expected, the polygenic score based on weights from an independent GWAS of educational attainment was associated with both educational and occupational achievement in both the parent and offspring samples (Fig. 1). Correlations (rs) ranged from .26 to .32 for educational attainment and from .19 to .24 for occupational attainment (Table S3).
Using these scores (not previously available to researchers of social mobility) they find:
Specifically, offspring who achieved a higher educational or occupational level than their parents tended to have higher polygenic scores than their parents. Conversely, children who fell short of their parents’ social achievements tended to have polygenic scores that were lower than their parents.
In the past it was not possible to buttress a genetic hypothesis with genomic analysis, but now polygenic risk scores afford that possibility. The authors are cautious in their interpretation, but it is pretty clear that we are moving towards (partial) causal explanations. This will change the social sciences in a profound way.
Some key points from their discussion section:
We found that a majority of individuals from the least advantaged homes achieved more educationally and occupationally than their parents, and conversely, a majority of individuals from the most advantaged homes achieved less. Our study implicated offspring–parent skill differentials as contributing to the considerable reordering of social standing that we observed across generations. Individuals rarely moved down and frequently moved up when they were more skilled than their parents.
We believe that a reasonable explanation of our findings is that the degree to which individuals are more or less skilled than their parents contributes to their upward or downward mobility.
Although offspring inherit all of their genes from their parents, they inherit a random subset of parental alleles because of meiotic segregation. Consequently, some offspring inherit a favorable subset of their parents’ alleles, whereas others inherit a less favorable subset. We found, as did previous researchers (Belsky et al., 2018), that the inheritance of a favorable subset of alleles was associated with an increased likelihood of upward mobility, whereas inheriting a less favorable subset was associated with an increased likelihood of moving down.
In summary, our analysis of inter-generational social mobility in a sample of 2,594 offspring from 1,321 families found that (a) most individuals were educationally and occupationally mobile, (b) mobility was predicted by offspring–parent differences in skills and genetic endowment, and (c) the relationship of offspring skills with social mobility did not vary significantly by parent social background. In an era in which there is legitimate concern over social stagnation, our findings are note-worthy in identifying the circumstances when parents’ educational and occupational success is not reproduced across generations.
Whatever your social background, if you are brighter than your parents, you generally rise; if less bright, you generally fall.