Using DNA to predict intelligence

Implications of the genomic revolution for education research and policy

Research at the intersection of social science and genomics, 'sociogenomics', is transforming our understanding of the interplay between genomics, individual outcomes and society. It has interesting and maybe unexpected implications for education research and policy. Here we review the growing sociogenomics literature and discuss its implications for educational researchers and policymakers. We cover key concepts and methods in genomic research into educational outcomes, how genomic data can be used to investigate social or environmental effects, the methodological strengths and limitations of genomic data relative to other observational social data, the role of intergenerational transmission and potential policy implications. The increasing availability of genomic data in studies can produce a wealth of new evidence for education research. This may provide opportunities for disentangling the environmental and genomic factors that influence educational outcomes and identifying potential mechanisms for intervention.

Why are there differences across German states in student achievement and cognitive ability?

Background

For more than twenty years, large and generally stable differences in academic achievement and cognitive ability have been reported within Germany. In such studies, the southern regions lead in the west and east, while city-states lag behind. Expressed in school learning time, the students in Bavaria are 14 months ahead of the students in Bremen. It is striking that there are no or only marginally received studies on causes and consequences.

Purpose

This study attempts to explore the causes and consequences of the differences within Germany and what can be learned in general about their development.

Materials and methods

We use data from student assessment and other studies (e.g., PISA, IQB) and apply correlational and path analyses, controlled for various background factors.

Results

There are no stable correlations with evolution (genes), educational level of society (adult school years) and wealth (GDP per capita). However, there are high correlations, robust across indicators, with "burgher-conservative" education policies, e.g., central exit examinations, early tracking, grades at a young age (around r ≈ .65); with measures of students' quantity of education (hours of instruction, no teacher shortage; r ≈ .40); with measures of tertiary educational quality and appreciation of education (university quality, short duration of studies, professors' salaries; r ≈ .50); with student native/immigrant ratio (r ≈ .50); with middle-class burgher lifestyle (less private debt, less welfare dependency and less crime; r ≈ .60); and with burgher-conservative-right politics (share of votes for CDU/CSU and non-left parties, non-left state governments; r ≈ .80). Longitudinal analyses over four decades reveal interaction effects, i.e., more burgher policies statistically lead to more cognitively competent students (β ≈ .45) and more cognitively competent populations vote for burgher parties (β ≈ .30).

Conclusions

The results, which support the efficacy a bourgeois-conservative education policy and of lower immigration rates, are delicate for the practice of student achievement research and for the political milieu that dominates the social sciences.

Rank concordance of polygenic indices

Polygenic indices (PGIs) are increasingly used to identify individuals at risk of developing disease and are advocated as screening tools for personalized medicine and education. Here we empirically assess rank concordance between PGIs created with different construction methods and discovery samples, focusing on cardiovascular disease and educational attainment. We find Spearman rank correlations between 0.17 and 0.93 for cardiovascular disease, and 0.40 and 0.83 for educational attainment, indicating highly unstable rankings across different PGIs for the same trait. Potential consequences for personalized medicine and gene-environment (G × E) interplay are illustrated using data from the UK Biobank. Simulations show how rank discordance mainly derives from a limited discovery sample size and reveal a tight link between the explained variance of a PGI and its ranking precision. We conclude that PGI-based ranking is highly dependent on PGI choice, such that current PGIs do not have the desired precision to be used routinely for personalized intervention.

Increasing pressure on US men for income in order to find a spouse

In contemporary societies, social status - especially income - is one of the most important determinants of ever marrying among men. Using U.S. census data, we estimated the importance of income for ever marrying among men and women, analyzing birth cohorts from 1890 to 1973. We examined individuals between the ages of 45 and 55, a total of 3.5 million men and 3.6 million women. We find that for men, the importance of income in predicting ever being married increased steadily over time. Income predicted only 2.5% of the variance in ever marrying for those born in 1890-1910, but about 20% for the 1973 cohort. For women, the opposite is true: the higher a woman's income among those born between 1890 and 1910, the lower her odds of ever being married, explaining 6% of the variance, whereas today a woman's income no longer plays a role in ever being married. Thus, our results provide evidence that income may represent a very recent selection pressure on men in the US, a pressure that has become increasingly stronger over time in the 20th and early 21st centuries.

The next 10 years of behavioural genomic research

Background

The explosion caused by the fusion of quantitative genetics and molecular genetics will transform behavioural genetic research in child and adolescent psychology and psychiatry.

Methods

Although the fallout has not yet settled, the goal of this paper is to predict the next 10 years of research in what could be called behavioural genomics.

Results

I focus on three research directions: the genetic architecture of psychopathology, causal modelling of gene-environment interplay, and the use of DNA as an early warning system.

Conclusion

Eventually, whole-genome sequencing will be available for all newborns, which means that behavioural genomics could potentially be applied ubiquitously in research and clinical practice.

Foster care leads to sustained cognitive gains following severe early deprivation

This study examined longitudinal data from the Bucharest Early Intervention Project, a randomized controlled trial of foster care as an alternative to institutional care following exposure to severe psychosocial deprivation. We report data from 135 participants assessed in early adulthood (age 18 y). We find that 16 y after randomization occurred, those who had been randomized to high-quality foster care had significantly higher IQ scores (9 points, 0.6 SD) than those randomized to care as usual. Mediation analyses provide evidence that the causal effect of the intervention on cognitive ability in early adulthood could be explained, in part, by higher-quality caregiving and attachment security. These findings indicate that early investment in family care as an alternative to institutional care leads to sustained gains in cognitive ability. Fostering caregiving relationships is a likely mechanism of the intervention. In addition, exploratory analyses indicate that stable placements throughout childhood are associated with the greatest long-term gains in cognitive ability. Whether early interventions for infants and young children lead to lasting change has significant implications for decisions to invest in programs aimed at improving children's developmental outcomes.

Commentary: The origins of intellectual disability

Despite the importance and prevalence of intellectual disability (ID), its origins have not been well understood until now. Lichtenstein et al. report in this issue findings from a population-based sample four times larger than all previous family studies of ID put together (Lichtenstein et al., 2022). From more than four million people, 37,787 individuals were identified with ID. Relative risks (RRs) are reported for relatives of ID probands (55,000 first-degree, 55,000 second-degree, and 170,000 third-degree) as compared with matched relatives of individuals without ID. These relatives plus 400 pairs of twins in which at least one twin was diagnosed with ID yield an astonishing estimate of 95% heritability with no evidence for shared environmental influence in their model. Another important finding is that maternal half-siblings of ID individuals were at greater risk than paternal half-siblings, a maternal effect that could indicate X-chromosome linkage. Finally, profound and severe ID is etiologically distinct from the normal distribution, due in part to noninherited (de novo) genetic mutations and chromosomal abnormalities. However, 90% of individuals with ID are moderate or mild, and these represent the low end of the normal distribution of genetic influence on cognitive ability, which has important implications for DNA research on ID.

Using DNA to predict behaviour problems from preschool to adulthood

BACKGROUND

One goal of the DNA revolution is to predict problems in order to prevent them. We tested here if the prediction of behaviour problems from genome-wide polygenic scores (GPS) can be improved by creating composites across ages and across raters and by using a multi-GPS approach that includes GPS for adult psychiatric disorders as well as for childhood behaviour problems.

METHOD

Our sample included 3,065 genotyped unrelated individuals from the Twins Early Development Study who were assessed longitudinally for hyperactivity, conduct, emotional problems, and peer problems as rated by parents, teachers, and children themselves. GPS created from 15 genome-wide association studies were used separately and jointly to test the prediction of behaviour problems composites (general behaviour problems, externalising, and internalising) across ages (from age 2 to 21) and across raters in penalised regression models. Based on the regression weights, we created multi-trait GPS reflecting the best prediction of behaviour problems. We compared GPS prediction to twin heritability using the same sample and measures.

RESULTS

Multi-GPS prediction of behaviour problems increased from <2% of the variance for observed traits to up to 6% for cross-age and cross-rater composites. Twin study estimates of heritability, although to a lesser extent, mirrored patterns of multi-GPS prediction as they increased from <40% to 83%.

CONCLUSIONS

The ability of GPS to predict behaviour problems can be improved by using multiple GPS, cross-age composites and cross-rater composites, although the effect sizes remain modest, up to 6%. Our approach can be used in any genotyped sample to create multi-trait GPS predictors of behaviour problems that will be more predictive than polygenic scores based on a single age, rater, or GPS.

Genomics and justice: mitigating the potential harms and inequities that arise from the implementation of genomics in medicine

Advances in human genetics raise many social and ethical issues. The application of genomic technologies to healthcare has raised many questions at the level of the individual and the family, about conflicts of interest among professionals, and about the limitations of genomic testing. In this paper, we attend to broader questions of social justice, such as how the implementation of genomics within healthcare could exacerbate pre-existing inequities or the discrimination against social groups. By anticipating these potential problems, we hope to minimise their impact. We group the issues to address into six categories: (i) access to healthcare in general, not specific to genetics. This ranges from healthcare insurance to personal behaviours. (ii) data management and societal discrimination against groups on the basis of genetics. (iii) epigenetics research recognises how early life exposure to stress, including malnutrition and social deprivation, can lead to ill health in adult life and further social disadvantage. (iv) psychiatric genomics and the genetics of IQ may address important questions of therapeutics but could also be used to disadvantage specific social or ethnic groups. (v) complex diseases are influenced by many factors, including genetic polymorphisms of individually small effect. A focus on these polygenic influences distracts from environmental factors that are more open to effective interventions. (vi) population genomic screening aims to support couples making decisions about reproduction. However, this remains a highly contentious area. We need to maintain a careful balance of the competing social and ethical tensions as the technology continues to develop.