The Genetics of Success: How Single-Nucleotide Polymorphisms Associated With Educational Attainment Relate to Life-Course Development

Abstract

A previous genome-wide association study (GWAS) of more than 100,000 individuals identified molecular-genetic predictors of educational attainment. We undertook in-depth life-course investigation of the polygenic score derived from this GWAS using the four-decade Dunedin Study (N = 918). There were five main findings. First, polygenic scores predicted adult economic outcomes even after accounting for educational attainments. Second, genes and environments were correlated: Children with higher polygenic scores were born into better-off homes. Third, children's polygenic scores predicted their adult outcomes even when analyses accounted for their social-class origins; social-mobility analysis showed that children with higher polygenic scores were more upwardly mobile than children with lower scores. Fourth, polygenic scores predicted behavior across the life course, from early acquisition of speech and reading skills through geographic mobility and mate choice and on to financial planning for retirement. Fifth, polygenic-score associations were mediated by psychological characteristics, including intelligence, self-control, and interpersonal skill. Effect sizes were small. Factors connecting DNA sequence with life outcomes may provide targets for interventions to promote population-wide positive development.

Keywords: adult development; behavior genetics; genetics; intelligence; personality.

Fig. 1.

Association between polygenic score and educational and adult achievement. In (a), mean polygenic score is graphed as a function of educational attainment. Error bars represent 95% confidence intervals. For the 1972–73 birth cohort we studied, compulsory education ended at age 15 years, at which point students could elect to take a School Leaving Certificate exam. Fifteen percent of our sample obtained no educational credential; 15% obtained the School Leaving Certificate but did not progress further; 42% completed sixth-form or Bursary Certificates (roughly equivalent to a full high school diploma in the United States); and 29% completed a university degree. In (b), the scatterplot (with best-fitting regression line) shows the relationship between Dunedin Study members’ polygenic scores (x-axis) and their adult-attainment-factor z scores (y-axis). The adult attainment factor was composed of occupational prestige, income, assets, credit problems, difficulties paying expenses, social-welfare-benefit use, and credit score. Each plotted point represents mean x and y coordinates for a bin of 10 Dunedin Study members.

Fig. 2.

Scatterplots showing the association between Dunedin Study members’ polygenic scores and their adult-attainment-factor z scores, separately for children born in low-, middle-, and high-socioeconomic status (SES) families. Each plotted point represents the mean x and y coordinates for a bin of about 10 Dunedin Study members. The solid red line is the best-fitting regression line for the raw data. The dashed lines show the mean level of attainment for each SES subgroup. The distribution of polygenic scores within each subgroup is shown in the box-and-whiskers plots at the bottom of the figure. The vertical line in the center of each box marks the median, and the left and right edges of each box correspond to the 25th and 75th percentiles, respectively. The whiskers indicate 95% of the range. The black vertical lines behind the box plots show the cohort mean. The plots align with the scales on the x-axes of the graphs.

Fig. 3.

Children with higher polygenic scores acquired reading skills more rapidly. Association between age and reading skill (as measured by the Burt Word Reading Test; Scottish Council for Research in Education, 1976), separately for children with high polygenic scores (≥ 1 SD above the mean; n = 159) and those with low polygenic scores (≥ 1 SD below the mean; n = 147). The shaded areas show 95% confidence intervals.

Fig. 4.

Association between polygenic score and likelihood of migrating out of New Zealand. The value at the end of each arrow is the average standard-deviation difference in polygenic scores (with the standard error of the estimate in parentheses) between Dunedin Study members who moved to that area (North America, n = 14; Europe, n = 41; Asia and Africa, n = 13; Australia, n = 162) and members who remained in or returned to New Zealand. Migrants were defined as Dunedin Study members who had lived and worked abroad for a minimum of 12 months since the age of 21 and who were still living abroad at the age-38 assessment.

Fig. 5.

Association between polygenic score and partner’s socioeconomic status (SES). The graph shows the percentages (inside bars) of members who had low-, middle-, and high-SES partners, separately for Dunedin Study members with low polygenic scores (≥ 1 SD below the mean; n = 119), average polygenic scores (within 1 SD of the mean; n = 504), and high polygenic scores (≥ 1 SD above the mean; n = 136). Partners’ SES was defined according to whether they had completed a university degree and whether their income was above the national sex-specific median: High-SES partners had a university education and an above-median income, middle-SES partners met only one of these criteria, and low-SES partners met neither criterion.

Fig. 6.

Association between polygenic score and cognitive ability. The plotted points in (a) show the magnitude of the effect of a 1-SD increase in polygenic score on standardized IQ (1 IQ point = 1/15 of 1 SD) measured at ages 3, 5, 7, 9, 11, and 13. Error bars indicate 95% confidence intervals. Cognitive ability was measured with the Peabody Picture Vocabulary Test (Dunn, 1965) at age 3, the Stanford-Binet Intelligence Scale (Terman & Merrill, 1960) at age 5, and Wechsler Intelligence Scales for Children–Revised (WISC-R; Wechsler, 1974) at ages 7–13. In (b), mental age is graphed as a function of chronological age for children with high polygenic scores (≥ 1 SD above the mean; n = 159) and those with low polygenic scores (≥ 1 SD below the mean; n = 147). The shaded areas show 95% confidence intervals. Mental age was measured with the WISC-R.