So let’s examine each of these research findings.
(1) ADHD is caused by genetics.
There are plenty of people with ADHD who do not have the genes associated with ADHD, and there are plenty of people without ADHD who have the genes associated with ADHD. We expect ADHD to run in families. People in families have similar bodies and experiences, so they are likely to learn similar ways. This, of course, is most pronounced with identical twins.
(2) Brain biology is different for those with ADHD.
The finding that ADHD brains are different only shows a correlation between people who respond with ADHD behaviors and certain kinds of biological patterns. It is reasonable to assume that doing ADHD behavior over time changes biological development just like what happens to muscle development when people don't exercise.
(3) Medicine works
We don’t know the cause of the problem just because medicine works. For example, alcohol might help a person to become more sociable, but that does not tell us why the person was not sociable.
Yes, your child’s biology changes the probably of what he learns. For example, if he is agile, he may enjoy playing sports, and if he has a gene associated with ADHD, his probability of an ADHD diagnosis rises a few percentage points from 9% to 13.5%. However, much can happen along the way to alter the course of his development. His genes do not seal his fate. Identical twins are often concordant for ADHD, but does not tell us how different they might become when exposed to very different kinds of environments. Children with similar starting points can learn to live in the world in very different ways. Your child’s high activity levels and other problems do not doom him to a lifelong pattern of ADHD behavior. There are ways to get ADHD behaviors to stop. You just have to know how to do it.