Pairs of both identical and non-identical twins are often used in genetic research because they still provide the basis for some of the best methods we have for teasing apart the relative contributions of genes and environment on various aspects of our mental and physiological make-up.
These methods, however, are not without their critics. The most significant reproach leveled against twin studies is the observational fact that data collected from such research projects may not always be accurate due to identical twins sharing not only a more similar genetic composition, but also more similar living environments.
Taking these complaints into consideration, a new study in Nature Scientific Reports looked at the role inherited traits and individual surroundings play in how well students do in tests required by the General Certificate of Secondary Education (GCSE).
In order to overcome said limitations of twin studies, in addition to the 2,245 identical and 4,071 non-identical twin pairs, the researchers also enrolled 7,432 genetically unrelated people, whose DNA was set for comparison.
Among twins, genetic factors explained between 54 and 65 percent of the test achievements; shared environment (like home and school) accounted for a further 14 to 21 percent; and individual environmental factors – each person’s unique experiences – comprised the final 14 to 32 percent.
After controlling for IQ – another important determinant of academic success – genes dropped down the scale of importance, but still came out as a major contributor, capable of explaining anywhere between 45 to 65 percent of the difference.
Even though results obtained from genetically unrelated participants showed a somewhat weaker correlation, they painted the same general picture, nonetheless – highly DNA-dependant traits like mental health, personality and motivation are key to getting ahead in school and, presumably, other environments that require skills for quickly learning and retaining large amounts of new information.
Claims about the importance of the ever-mysterious and enigmatic “genes” on how well children do in the classroom have always been controversial – reports on the interplay between “nature” and “nurture” are always in danger of giving off the implication that low-achieving students are dead-set in their ways and should be simply abandoned in favour of naturally brighter kids.
With this hazard clearly in view, the study authors emphasised that their intentions have nothing to do with blame or discrimination, and everything to do with developing individualised educational models to help each child reach his or her maximum potential.
While no single study is reason enough to overhaul a national school system, it still provides an interesting confirmation of the folk-psychology insistence that traits other than intelligence are important, too.