Epigenetics is the addition or removal of molecules that are attached to (“on top of”) our DNA or genes. These molecules direct the genes to work so that our cells and our bodies function normally. But things in the environment, such as tobacco smoke, may change the way these molecules are added or removed to our genes, causing the genes to not work properly.

Epigenetics literally means “on top of genetics.”

Changes in epigenetics can increase the risk of ADHD.