The breeding suggests that genetics play a role in how motivated the rats are, and it could be indicative of genetic laziness in humans. "We have shown that it is possible to be genetically predisposed to being lazy," Booth said in a statement announcing the study's publication.
The researchers observed dozens of rats and how much they ran on a wheel voluntarily for six days. Next, they bred the 26 that ran the most with each other, and the 26 that ran the least with each other. After doing this breeding through 10 generations of rats, they found that the "super runner" rats ran 10 times more than the "couch potato" rats.
They then sequenced the rats' RNA and found some genetic differences, which could show that motivation and activity are in the genes. "Out of more than 17,000 different genes in one part of the brain, we identified 36 genes that may play a role in predisposition to physical activity motivation," Roberts said.
It's probably a good idea to skip the gym this weekend and call your parents to complain about your genetic stock. It's all their fault that you'd rather lie around watching The Walking Dead on a loop than get in a brisk 5k.