Neuroscientist Robert Sapolsky says nearly all aspects of human behavior are explained by biology: from developments millions of years in the past to microscopic reactions happening in the present.

Many think genetic makeup is fixed from the moment we're born. But Moshe Szyf  says this understanding is incomplete because our experiences and environment have the power to change our basic biology.

Pediatrician Nadine Burke Harris found an unsettling trend when examining patients at her clinic: trauma. She found that adversity can change a child's biology and result in severe health outcomes.

Are you introverted or extroverted? It depends. When it comes to personality traits, Brian Little says we can actually act against our biology -- especially if we pursue a "core life project."