Education is supposed to level the playing field for poor children. Armed with a good education, they should be able to compete with their more affluent peers as they grow up and match them stride for stride as they enter the world of work…

Alas, for almost as long as that sentimental notion has been guiding aspects of educational policy, educators have had to acknowledge that children from low-income families too seldom overcome their initial disadvantages.

So programs like Head Start in the US were set up to help poor kids prepare for school. And, indeed, research has shown that some “school readiness” programs work. An enriching preschool experience can help certain children to do better in school over the longer term.

On another tack, a group of Canadian researchers has lately been investigating whether genes play any role in conditioning children’s readiness for school. Does an enriching early environment really help to level the playing field, or will some kids be for ever hampered by their genetic makeup?

Jean-Pascal Lemelin and his colleagues at the Université Laval in Québec, as well as researchers from the Université de Montréal and the Université du Québec à Montréal compared fraternal and identical twins. Twin research is a common way to tease apart the influences of genes and environment.

The basic idea is: if something in the twins’ environment accounts for their school readiness, then identical twins (who are genetic duplicates of one another) should be no more similar in their readiness than fraternal twins (who share, on average, only 50 percent of their genes).

The researchers followed 420 pairs of five-year-old identical and fraternal twins. They assessed them on four measures of school readiness concerning colors and shapes, spatial relations, numbers and counting, and letters and writing. Two years later, the children's teachers were asked to rate the school achievement of 237 pairs. Twins also took a standardized test of general cognitive ability.

The research team found that the twins’ shared experiences at home, in preschool, and other environments contributed substantially to their readiness for school. Although not as important as the “shared environments", genes contributed to children’s general abilities.

"Our results have important implications for preventive interventions," said Michel Boivin, Canada Research Chair in Child Social Development and professor of psychology at Laval University in Quebec City and one of the study's authors. Quoted in Science Daily, he added, "They should be seen as a further incentive for continued implementation and evaluation of preventive intervention programs aimed at improving the level of school readiness in children from at-risk families."

It’s still not the end of the story. What aspects of the kids’ early environments make a difference is still not clear. Do the key ingredients for school readiness lie in the interactions between parents and children? In preschool curricula? In the types of activities parents encourage? Answers to such questions might further the enduring effort to level the playing field.

• For more about preschool programs, see these Prevention Action stories:
Can several thin reeds ever make a strong policy boat?
The pros and cons of early years programs: where to start?
Getting the measure of the mileage of preschool care

• Summary of “The Genetic–Environmental Etiology of Cognitive School Readiness and Later Academic Achievement in Early Childhood” by Jean-Pascal Lemelin, Michel Boivin, Nadine Forget-Dubois, Ginette Dionne, Jean R. Séguin, Mara Brendgen, Frank Vitaro, Richard E.; Tremblay, and Daniel Pérusse in Child Development, Nov 2007, Vol. 78 Issue 6, pp1855-1869.