Alas, the only definitive assertion in this comment chain. It has been proven that there is a genetic component to ADHD, not that it is exclusively a genetic disorder.
I also believe ADHD is partially environmental. I have diagnosed with and am treated for it.
It’s not anti-science to believe something that hasn’t been disproven. It is anti-science to believe something that has been disproven (e.g. climate change-denying loons).