"The only thing you have to fear is fear itself," so goes the old saying. Regardless of whether you believe that or not, you may want to consider this: according to a study conducted by the Virginia Commonwealth University, genes play a part in determining what we fear.

The study was led by one Kenneth S. Kendler, M.D., professor of psychiatry and human genetics. Kendler and his fellow researchers evaluated fear factors among 2,500 pairs of twins born between 1985 and 1986.

The twins completed a questionnaire containing 13 items related to fear. Kenneth asked the participants to rate their fear on a scale of 0 (no fear) to 10 (maximum fear). The researchers also asked the twins' parents to rate their children's fear intensity using the same scale.

According to Kendler, the dynamic nature of the human genome influences the kinds of fears we have as it adapts to the person's developmental situation. This explains why our fears tend to change as we grow from childhood to adulthood.