You may want to thank the genetic lottery for your funny bone (or lack thereof). A recent study found that those who smiled or laughed the most at funny comics or film clips had shorter versions of the 5-HTTLPR gene that regulates serotonin—a brain chemical that influences our moods, including our susceptibility to depression or anxiety. Meanwhile, those with longer version of the gene were less amused. According to researchers, people with shorter versions may thrive in positive environments and struggle in negative ones whereas those with longer versions are less sensitive to these outside factors. Which side of the 'nature versus nurture' debate do you fall on? Do you think that genetics could influence our sense of humor or does our environment play more of a role? Sound off in the comments.