What you have just read is true. In fact, a recent study conducted by the University of Missouri suggests that some genes may predispose to laziness and this might justify the fact that approximately 97% of American adults get less than 30 minutes of exercise a day, which should be the minimum amount to maintain a healthy lifestyle.
The study was carried out by Professor Frank Booth and Michael Roberts, Post-Doctoral Fellow at the Missouri University College of Veterinary Medicine and was published in the “American Journal of Physiology: Regulatory, Integrative and Comparative Physiology”. During the experiments, some male and female rats were put in containing running wheels cages and the running willingness of each animal was measured over a six days period. The next step was to select the 26 most “sporty” rats and the 26 laziest rats and bred each other the animals within the two groups. The same selection process was repeated through ten generations and, in this way, two different groups of rats could be selected: the first one showed a high willingness to run, whereas the second one showed a low willingness to run (ten times less then the other group). Once these two groups of animals were created, the levels of mitochondria in muscle cells and the genetic differences between the two groups of animals were studied. As a result, 36 genes that could be involved in the genetic predisposition to being more or less motivated to exercise were identified. This interesting result might be useful to find out additional causes to obesity in humans. Further researches will be conducted using these animal models, in order to obtain more information on the effects of each gene that was identified in this study on physical activity motivation.