I’m sorry, but your individual anecdotal experience does not refute his hypothesis in any way. It is reasonable to hypothesize that the increase in ADHD may be due to environmental factors (diet / exercise / etc). Those factors may affect certain subgroups more than others. Your perceived offense is not helpful to the discussion because you cannot speak for all people with ADHD and it should not shut down any line of inquiry that could help people in the future. I completely understand that you are not considering yourself as part of that group, but please let other people try and find alternative ways to address the problem without trying to shut down the conversation by proclaiming how insulted and offended you are.