The Victorian Era
The Victorians had a great deal of faith in phrenology, or the "science" of using a person's head to determine their personality, intelligence, and overall character. Moleoscopy, a special subgenre of the practice, claimed to be able to identify character traits based on mole placement.
For example, those with marks on the right sides of their foreheads were considered extremely intelligent and competent. If your mole was on the left side of your forehead, though, you were probably just a spendthrift.