It turns out that children who don't like school aren't merely lazy, but could blame their lack of interest on the genes inherited from their parents, according to new research.

Researchers from Ohio State University studied more than 13,000 twins from six countries and found that 40 to 50 percent of the differences in children's motivation to learn could simply be explained by their DNA.

This came as a surprise, given that some scientists believed a shared environment - such as having the same family and teachers - would be a larger factor than genetics. However, it appears that genetics and nonshared environmental factors had the largest effect on learning motivation, whereas the shared environment had negligible impact.

"We had pretty consistent findings across these different countries with their different educational systems and different cultures," study co-author Stephen Petrill said in a statement.

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

"The knee-jerk reaction is to say someone is not properly motivating the student, or the child himself is responsible," Petrill said. "We found that there are personality differences that people inherit that have a major impact on motivation. That doesn't mean we don't try to encourage and inspire students, but we have to deal with the reality of why they're different."

During the study, researchers looked at sets of twins aged 9 to 16 in the United Kingdom, Canada, Japan, Germany, Russia and the United States. They measured how much each student enjoyed or liked various academic activities, including reading, writing and spelling. All students were also asked to rate their own ability in different subjects in school. 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.

On average, 40 to 50 percent of the difference between twins in motivation could be explained by genetics. Meanwhile, about the same percentage could be explained by a nonshared environment - for example, differential parenting or a teacher that one twin has but not the other.

It should be noted that these results don't suggest that there is a gene for how much children enjoy learning, but rather that liking school is a complex process involving many genes and gene-environment interactions, that help influence children's motivation to learn.

"We should absolutely encourage students and motivate them in the classroom. But these findings suggest the mechanisms for how we do that may be more complicated than we had previously thought," Petrill concluded.

The results were published in the journal Personality and Individual Differences.

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