What makes kids dislike school?

Study co-author Stephen Petrill asserted that they had pretty consistent findings across these different countries with their different educational systems and different cultures.

The results strongly suggest that they should think twice before automatically blaming parents, teachers and the children themselves for students who aren't motivated in class.

The study involved separate studies of twins aged 9 to 16 in the United Kingdom, Canada, Japan, Germany, Russia and the United States. The study methodology and questions in each country were slightly different, but all measured similar concepts.

All students were also asked to rate their own ability in different subjects in school . For example, in the United States, students were asked to rate how much they agreed with statements like "I know that I will do well in reading next year."

The researchers compared how close the answers were for fraternal twins, who share half their inherited genes, on average with identical twins, who share all of their inherited genes and to the extent that identical twins' answers were more closely matched than those of fraternal twins, that suggests a stronger genetic effect.

Petrill said that the results were strikingly similar across all six countries with children of all ages and on average, 40 to 50 percent of the difference between twins in motivation could be explained by genetics and about the same percentage could be explained by what was called the twins' nonshared environment, for example, differential parenting or a teacher that one twin has but not the other. Only about 3 percent could be explained by their shared environment, such as their common family experience.

The study is published in the journal Personality and Individual Differences.