With both depression and suicide, research suggests that causal factors are a combination of genetics and environment, Peterson said.

CNN: Suicidal behavior may run in families

Despite findings in recent research studies that conclusively refute the causal link between violence in video games and aggression in children, the speculation about such a causal link continues in the political sphere.

FORBES: Senator Rockefeller Quotes Experience, Believes That Evidence Proves Violent Movies and Games Cause Aggressive Behavior in Kids

Because these studies are mainly observational, extensive research is under way to determine the causal relationship between vitamin D levels and disease as well as the role of increasing vitamin D intake.

CNN: How much vitamin D do I need?