According to Over or under? The science of toilet paper orientation and Over or under? The great toilet paper debate
... some studies suggest that the answer is more than coincidence. For instance, people who orient their rolls “over” are more organized and characterized as over-achievers. ... This group represents 70 percent of the people who actually care that much about toilet paper. The remaining 30 percent of this peculiar study group are the “unders”. Characterized as “laid-back”, “artistic”, and “dependable”.
Is there really evidence that one's preference has any correlation with one's personality, and if so, why?