In dit artikel verken ik de laatste wetenschappen in moleculaire biologie en hoe onze genetische makeup gelinkt is met ‘successen’ die we boeken in het leven.
Er zijn, vind ik, weinig wetenschappelijke velden die zo interessant zijn als deze. De kennis die we opdoen in genetisch onderzoek en specifieker de link tussen onze genen en onze intelligentie en gedragingen gaat razendsnel. Wellicht te snel voor het gewone volk in de westerse wereld vanwege associaties met de nazi’s en de Tweede Wereldoorlog, maar de wetenschap heeft niet stil gestaan. Zeker in China zijn ze al sinds 1999 met miljarden aan subsidies bezig met het sequencen van het menselijk genoom in de Beijing Genomics Institute en het proberen te vinden van genen die gerelateerd zijn aan onze intelligentie en gedrag. Het mappen van genen van het menselijk genoom kostte in 1990 nog $2,7 miljard, maar kan nu worden gedaan voor ongeveer $1.000.
Je kan je ogen sluiten voor deze ontwikkelingen, maar het feit blijft deze wetenschap zich door blijft ontwikkelingen. Naar verwachting zullen er talloze toepassingen zijn die voort zullen komen uit de kennis in dit veld. Ik verwacht dat het ons in de toekomst medicijnen zal bieden tegen alzheimer en dementie, maar ook middelen zal voortbrengen die onze cognitieve capaciteiten een boost kunnen geven. Er zijn uiteraard ook ethische kwesties zoals de vraag of embryologen niet alleen embryo’s mogen screenen op ziektes, maar ook op een genetische makeup die optimaler is voor het boeken van successen in het leven.
In het artikel grijp ik voornamelijk terug naar het onderzoeksrapport van Belsky dat enkele maanden geleden was gepubliceerd. Dit onderzoek is een mijlpaal! Wetenschappers hadden in 2013 al wel een genetische map gemaakt van genen die van invloed zijn op onze intelligentie en de kansen waarop we school succesvol kunnen afronden, maar voor zover ik weet is dit het eerste onderzoek dat een link legt tussen onze genen en successen die verder gaan dan educatie alleen.
Ik heb het artikel in het Engels geschreven. Je kan het hieronder vinden.
Warning: this post is not for egalitarians who believe that everyone is equally beautiful and talented or that everyone can become an Aristotle through immense self-effort. No, this post argues that our genetic differences result in different expected life outcomes.
We are living in extremely interesting times. It seems that we have reached a tipping point in genomic research. We can now predict life outcomes based on genetic tests. Daniel Belsky from Duke University and his team of researchers have recently released a paper asserting that genetic tests can predict adult life outcomes. The magnitude of correlation between genomic tests and adult life outcomes is still modest, but the predictions will grow more accurate once we gain more knowledge about the genetic makeup of ‘success’. I believe that this is big news, since this is the first well-developed psychometric/genetic research I have read so far that proves that life success is too some extent related to our genetic makeup.
When Belsky et al looked at the genetic profiles and the people they studied, they found that people with higher polygenic scores did not only have greater educational attainments, but also had more prestigious occupations, higher incomes, more assets, greater upward social mobility, were more likable and friendly.
Main research findings
The main research findings can be summed up as follow:
- polygenic scores predicted adult economic outcomes even after accounting for educational attainments;
- genes and environments were correlated: Children with higher polygenic scores were born into better-off homes;
- 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;
- 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;
- polygenic-score associations were mediated by psychological characteristics, including intelligence, self-control, and interpersonal skill.
Belsky’s main research question
In 2013, Rietveld et al reported the first successful genome-wide association study (GWAS) of educational attainment. They analyzed millions of genetic variants in more than 100,000 individuals and found a genetic map that was related to people’s educational attainment. This genetic map could even explain differences in educational attainment between siblings in the same family.
The main research question that Belsky et al ask is: “do genetic discoveries for educational attainment predict outcomes beyond schooling?”
If so, what are the developmental and behavioral pathways that connect differences in DNA sequences with divergent life outcomes?
Belsky’s research methodology
1,037 people born between April 1972 and March 1973 in Dunedin, New Zealand, were tracked through a 38-year assessment of their socioeconomic development. This study became known as ‘the Dunedin study’. The cohort represented the full range of socioeconomic status (SES).
The researchers derived polygenic scores from the approximately 2.3 million genotypes that according to Rietveld et al would make up the genetic predisposition to educational attainment. In addition, adult-attainment scores were derived from extensive analyses of Dunedin members’ life developments. See table 1 for developments that were tracked and the methods through which these developments were measured.
The researchers have for example measured SES, determined from the higher of either parent’s occupational status throughout the Dunedin Study members’ childhoods. Educational attainment was measured, looking at the highest obtained degree. Attainment beyond education were measured by members’ reports of occupation, income, assets, credit problems when they were 38 years old and from social welfare and credit-score records. Reading abilities, taken when the Dunedin Study members were 7, 9, 11, 13, 15, and 18 years old, were measured as well. What I find extremely interesting is the fact that the researchers have measured not only cognitive ability through picture vocabulary tests and IQ tests, but also certain personal traits like self-control, impulsive aggression, hyperactivity, lack of persistence, inattention and interpersonal skills.
More substantive research results
I will list all research results here:
- people with higher polygenic scores tended to achieve higher degrees;
- people with higher polygenic scores tended to be more socioeconomically successful, holding more prestigious occupations, earning higher incomes, having more assets, relying less on social-welfare benefits, having higher credit scores and reporting fewer difficulties paying expenses;
- children with higher polygenic scores tended to come from families with higher SES;
- children with higher polygenic scores tended to attain more regardless of whether they began life in a family of low SES or high SES. Children from low SES with high polygenic scores tended to have greater upward social mobility than their low SES peers with low polygenic scores;
- children with higher polygenic scores were more likely to talk earlier and quicker to begin communicating using sentences;
- children with higher polygenic scores were able to read at younger ages;
- adolescents with higher polygenic scores had higher educational aspirations at the age of 15;
- adolescents with higher polygenic scores performed better academically and outperformed their peers on standardized tests;
- people with higher polygenic scores were more likely to pursue occupational opportunities outside of New Zealand;
- people with higher polygenic scores were more financially planful;
- people with higher polygenic scores tended to find partners with higher socioeconomic attainments;
- people with higher polygenic scores were not more satisfied with their lives;
- people with higher polygenic scores performed better on IQ tests and showed more rapid cognitive development during childhood;
- people with higher polygenic scores had stronger noncognitive skills, such as self-control, friendliness, confidence, being cooperative and communicative;
- children with higher polygenic scores were no healthier than their peers.
Knowing that our genetic makeup partly determine our success in life, would it be ethical to screen embryos for genetic signs of success in life? In some cases, embryologists already check embryos for major diseases, but should we allow parents to select embryos with the greatest genetic odds of future success?
These are interesting questions that, I believe, we will be facing in the near future.
Belsky et al – The genetics of success