Everyone has anxious moments where their hands sweat, their stomach churns and sleep seems impossible. But what causes these moments - the situation, their upbringing or a certain gene? A question like this evokes an old debate: nature or nurture?

There are two distinct positons held on this topic. There are the nativists, who believe we are products of our heredity or genetic code. The other position are the empiricists "Their basic assumption is that at birth the human mind is a tabula rasa (a blank slate) and that this is gradually 'filled' as a result of experience (e.g. behaviorism)," as reported in SimplyPsychology.org. For all practical purposes, no one today takes either extreme as fact. According to Saul McLeod, "There are simply too many 'facts' on both sides of the argument which are inconsistent with an 'all or nothing' view." Today researchers are trying to figure out what percentage of each makes a person.

According to nativists, brain research has narrowed anxiety and depression down to two chemicals in the brain: serotonin and norepinephrine. The lack of these can cause anxiety and depression. Depending on how much is missing, the results can range from mild anxiety to General Anxiety Disorder, according to Gary D. Vogin, MD, on Web MD. If this research is correct then it is logical to conclude that those who have a genetic disposition to correct levels of these chemicals are much less likely to be unhappy than those who were not so genetically blessed. Prozac and other drugs help compensate for those lacking that gene.

According to empiricists, experiences can affect a person's level of anxiety. If someone goes through a traumatic event like war, a personal loss or the death of a loved one, then it's only normal for anxiety to become worse and worse. "Once the person learns to deal with this traumatic experience and then learns the proper skills to manage the anxiety, then he or she is able to drive while experiencing little to no anxiety at all," The Anxiety Support Network explains. People can learn different strategies to cope with the feeling.

The bottom line is, anxiety is affected by both nature and nurture. It's partly genetic and partly experience that makes people who they are. Science can tell the reason for anxiety, and tell us how to fix it, but science can't keep us from it.