Gym Rats Can Thank Their DNA

People driven to pump iron or chill out on the sofa may differ as much in their DNA as they do in their activity levels, reports the Los Angeles Times. Scientists have discovered that identical twins are twice as likely to have similar workout habits as fraternal twins, indicating exercise may be linked to genetics.

Results from more than 20 studies of identical twins—genetic duplicates—and fraternal twins—who share half their genes—are nearly unanimous. Genetic make-up appears to account for as much as 78% of an individual's desire to do physical activity, say researchers. Hoping to dermine why, scientists have bred a strain of super-runner mice in a bid to discover how they process dopamine differently than regular mice.
(More DNA stories.)