This should be a no-brainer: in an era when increasingly words like ‘gene-environment interaction‘ are bandied around, it would be self evident that for full flowering of a prototypical trait, the genotype has to get the right environmental inputs. In absence of the right environmental conditions, the genetic differences may be masked and the trait under consideration suffer from universal stunted growth, thus even different genotypes leading to same phenotype -that of survival trait. contrast this with the condition where the environment provides rich conditions for the flowering of the trait under consideration. Here the trait will be having maximal value and would be a thriving trait value. Here genotype differences , if any , would be accentuated and become visible as difference sin phenotype expression.
If the above is a bit abstract , take the concrete example of SES and the corresponding low environmental condition and its relation to IQ/brain/cognitive ability. In an impoverished environment differences due to genetics would be masked and everyone will have a low IQ/cognitive ability. As opposed to this in an enriched environment condition, not only the average IQ would be higher (a thriving condition), there would be more differences in the IQ of children/people concerned as the right environment will make it possible for genetic effects to come into play and determine the IQ/cognitive ability. The above is a bit paradoxical and counter-intuitive- one advocates environmental interventions only to see that effects of environment becoming less for the trait and effects due to genetics becoming more prominent as more and more conducive environment is provided. The rationale for providing the right enriched environment /high SES to all would thus be not to eliminate inequality (inequality would paradoxically be accentuated) ; but to raise the trait value to maximum possible under the right environmental and that perhaps is for the good of all.
I have debated this issue earlier in my low IQ and SES series of posts, but thought will comment on the same in light of two articles that I cam across recently. The first article is a bit old, but has the devastating effect of waking one form ones slumber as one realizes that low SES leads to brain effects in low SES children that are akin to those faced by normal children/people who suffer brain damage due to stroke etc. I came across this via this science daily release tweeted by someone today (forgot the source).
The second study is a brand new one , published just today (and I have just read the extract and accompanying Sci Am article). The study, using identical and fraternal twin studies, in essence found that children’s reading ability was largely genetic (82 % genetic component), but that teacher quality mattered a lot. The genotype was able to flower fully when teacher was high h=quality- not only the reading ability was better; differences were accentuated. In contrast, when teacher quality was low, environmental had a much stronger effect by leveling everyone to a smaller value. To quote from the article:
“When children receive more effective instruction, they will tend to develop at their optimal trajectory,” said study lead author Jeanette Taylor in a prepared statement. “When instruction is less effective, then children’s learning potential is not optimized and genetic differences are left unrealized.”
The researchers found that good instruction promoted stronger reading development. Without it, children were less likely to reach the potential conferred by their genes. “When teacher quality is very low, genetic variance is constricted, whereas, when teacher quality is very high, genetic variance blooms,” they report. While teacher quality appears to be an important contributor, other classroom factors, such as classmates and resources, might also influence reading ability, the researchers noted.
To me, the results are important, though self-evident. Hopefully they will seal the endless confusion on the matter and allow a more reasoned dialogue and intervention to happen where IQ and SES/enriched environment is concerned.
Taylor, J., Roehrig, A., Hensler, B., Connor, C., & Schatschneider, C. (2010). Teacher Quality Moderates the Genetic Effects on Early Reading Science, 328 (5977), 512-514 DOI: 10.1126/science.1186149
Kishiyama, M., Boyce, W., Jimenez, A., Perry, L., & Knight, R. (2009). Socioeconomic Disparities Affect Prefrontal Function in Children Journal of Cognitive Neuroscience, 21 (6), 1106-1115 DOI: 10.1162/jocn.2009.21101