Causes of ADHD on Newsfeed -Scientists still don't know exactly what causes ADHD but here are some factors that may contribute to it. Heredity. If your parents couldn't get all the way through singing Happy Birthday without getting distracted, there's a good chance you have that gene too. Exposure to toxins during pregnancy. If your mom was partying like its 1999 in 1989 and got pregnant, you're more likely to have got some Adderall with your Flintsone chewables. And brain trauma. If you have some damage to your frontal lobe, you might get diagnosed with ADHD. So, yeah, it’s probably a good idea to not let your 3 year-old go x-games on his tricycle in the backyard.