Known as a ‘singular palmar crease’ or ‘simian crease’, this feature happens in around a third of people, and while it happens in perfectly healthy people, it can occur in people with Down's syndrome, fetal alcohol syndrome, Turner syndrome, Aarskog syndrome and Rubella sydrome.
While the practice of palmistry would have us believe each of the three major lines on our palms can tell us about our heart, head, and life, there is a scientific reason behind the criss-crossing patterns on your palms.
According to the Business Insider, these lines start appearing when a baby is only 12 weeks old in the womb. The lines function as creases in the thick skin of the palms of our hands, and make it possible for us to close and open our hands and grab on to things.
The number of lines you are born with can tell you interesting things about your health too. While most people are born with three lines, some people are born with just one.