Overcoming genetic propensity to poor reading
I am going to do two successive posts related to children’s reading. In this first one, Leve et al. (2022) published “The Potential of Children's Rearing Environment to Overcome Genetic Propensity for Low Reading Achievement” in Mind, Brain, and Education. Here’s the edited article:
Genetic studies show that children's reading achievement is in part genetically influenced, and intervention studies show that reading achievement can be increased by environmental interventions. The parent-offspring adoption design offers a novel opportunity to examine the independent and joint roles of genetic and rearing environmental contributions. Results indicated that adoptees' reading scores were correlated with their biological parents' scores, but not with their adoptive parents' scores, suggesting genetic influences. In addition, examination of mean scores indicated that adoptees' scores were significantly greater than their biological parents' (p's < .001) for all subtests, suggesting promotive effects of the rearing environment. This pattern was present even when biological parents scored >1 standard deviation below the biological parent mean on achievement.
There is unambiguous evidence from twin studies that reading achievement has a genetic component. Molecular genetic studies also provide evidence of genetic influences on reading achievement, although findings regarding specific single nucleotide polymorphisms have not been consistently replicated. In general, polygenic scores (PGS) associated with overall educational attainment in independent general population samples have accounted for 7%–10% of the variance in specific cognitive performance. However, because PGS show weak prediction, on their own they cannot inform education policy. Moreover, as behavioral genetic researchers have long emphasized (e.g., Plomin, 1999), the heritability of a cognitive trait does not mean that it is immutable. Rather, it is increasingly recognized that environmental contexts modulate the expression of heritability, and thus, genetic influences need to be investigated in tandem with potentially modifiable environmental factors (e.g., school, family).
Despite the impressive results from intervention studies, to our knowledge, reading intervention studies have not ascertained whether reading interventions work better for children who are genetically predisposed to be successful readers. Another observation is that many familial and extra-familial social risks and protective factors for reading achievement, such as family discord/coherence, parent–child hostility/warmth, and peer victimization (often experienced in school settings), are also shared within families. In biological families, associations between characteristics of the parent and characteristics of the child may result from underlying shared genetic characteristics that simultaneously influence both the trait in the parent and the trait in the child.
Participants were N = 344 linked sets of adopted children, adoptive parents, and biological parents participating in a longitudinal, multisite study of children adopted at birth in the United States, recruited in partnership with 45 adoption agencies from 15 states. In addition to the 344 adopted children, their biological mothers (n = 296), biological fathers (n = 96), adoptive mothers (n = 320), and adoptive fathers (n = 251) also completed the achievement assessment. Eligibility criteria for participation in the original EGDS study included: (1) the adoption placement was domestic, (2) the infant was adopted within 3 months of birth (M = 5.58 days, SD = 11.32 days), (3) the infant was placed with a nonrelative family, (4) both the biological parents and adoptive parents were able to read or understand English at an eighth-grade education level, and (5) the infant did not have any major medical conditions. All assessments were administered in English and all children spoke English as a first language. This report focuses on an assessment of reading achievement conducted when children were in the first-grade of elementary school and were approximately 7 years old.
We replicated prior findings suggesting that children's reading achievement has a genetic component by showing that adoptees' reading scores were correlated with their biological parents' scores, even though they were not raised by them. As such, adoptees and their biological parents demonstrated rank-order similarity in reading achievement. We also showed that adoptees' mean-level reading scores were more similar to their adoptive parents' scores than they were to their biological parents' scores, suggesting that the rearing environment can have a profound effect on children's reading achievement, even when biological parents have low reading levels.
The findings suggest that even when a child might be at genetic risk for reduced reading achievement, rearing environments can have a positive effect on indicators of reading, resulting in higher reading performance than would be predicted by genetic factors alone. In this study, the mechanisms underlying this positive rearing environmental effect could be an advantageous home literacy environment, school selection and associated education curricula, and/or parental involvement in school—all of which are potential components of effective education policy warranting further study. Because children's achievement was positively impacted by their rearing environment regardless of genetic predispositions, there is no evidence to suggest that providing different educational programming for children as a function of their genetic makeup would be beneficial. Moreover, such practices have the potential to perpetuate inequalities in access to advantageous educational programs that may increase achievement levels. In other words, if such policies were implemented, children with higher genetic risk may not be given the same educational opportunities as those with lower genetic risk, even though they would benefit from exposure to an enriched educational environment at similar levels as other children.
Taken together, the current results offer new insights into the importance of the early rearing environment for children's reading attainment as indexed by several indicators of reading skills, regardless of their genetic make-up.
I love the clever design and the carefully documented literature review and findings. It also highlights the importance of recognizing the reparative impact of adoptive parents’ environment on adoptive children.