If Donne were alive, he might revise his meditation to “No child is an island”. Or, more precisely, no twin is an island in the Florida public school system. Researchers published in Science last week that 1st and 2nd graders’ abilities to reach their genetic potential for learning (in this case, their achievement on the Oral Reading Fluency test) is positively moderated by their teachers’ abilities. That is to say, gene (student ability) by environment (teacher skill) interactions are important for early learning. When twins are taught by a highly skilled teacher, measured by reading gain achieved by non-twin classmates, much of their reading fluency is explained by genetics, and these children can be said to “develop at their optimal trajectory“. However, poor teaching impedes a twin’s natural ability to read well, hence there is a low genetic variance component, meaning “genetic differences are left unrealized“. This study is also a good introduction to how scientists address the age-old Nature vs. Nurture debate. When scientists talk about parsing the relative contributions of genes and environment to a trait, in this case, reading skill, monozygotic (identical) and dizygotic (fraternal) twins are the perfect test subjects because they share 100% and 50% of their genes, respectively. This allows researchers to estimate the environmental contribution to reading skill success variation for monozygotic twins, and then, deduce the additional contribution of genetic variation to reading skill variation for dizygotic twins (and this works out nicely in most cases because, for almost every trait, a dizygotic twin is more different from his twin than a monozygotic twin is to his).