Reading focus
Syllabus: Where Do Individual Differences Come From?
Follow the nontransmitted-score comparison while distinguishing educational attainment, cognitive ability, and specific family processes.
Why you’re reading it. See how measured DNA can help investigate environmental pathways while still leaving their mechanisms open.
A question to consider. How would information about Maya and Leo’s grandparents, aunts, and uncles help evaluate the claim that a parental-score association operates through their parents’ behavior?
Why this reading
Parental DNA that a child did not inherit offers a useful comparison when interpreting genetic associations. This study examines whether nontransmitted variants associated with education also predict offspring educational attainment, opening questions about pathways through families and their surroundings.
Before you read
A polygenic score aggregates many genetic associations; it is neither one gene nor a complete measure of inherited influence. Nontransmitted alleles are parental variants absent from the child’s inherited set. Educational attainment describes schooling achieved and is not interchangeable with intelligence. Assortative mating means partners resemble each other on characteristics relevant to the analysis.
Read for
- Trace the comparison between transmitted and nontransmitted parental scores.
- Distinguish evidence for an indirect association from identification of a particular parenting behavior.
- Interpret the reported ratio of score effects as a ratio of coefficients, not a percentage of education caused by nurture.
Consider afterwards
- A parent’s nontransmitted score predicts a child’s schooling. What additional family comparisons would help distinguish a process within the household from advantages shared across generations and relatives?
Editorial context
The study uses Icelandic data. A later meta-analysis finds related associations across cohorts while noting ancestry and design limits. Nivard and colleagues’ extended-family study questions how much of the signal can be attributed specifically to processes within the nuclear family. ‘Genetic nurture’ should therefore not be read as a measured quantity of good parenting or a uniquely identified environmental mechanism.