Humans didn't develop in a world like this, living in concrete rat runs (cities). Males used to go hunting and maybe fishing, every day but it was a strenuous life. Adrenaline and testosterone played a big part in their lives. Who needs that now? Now kids who should be out running around and learning life skills to survive in the world are shut up in multi-level apartments, in a school room all day, or they go to a park now and then. Their fathers aren't around teaching them about the world because they don't know, either. They usually can't even fix things like guys did through the 60s. No wonder boys (mostly) have problems. ADD was likely never present before it was 'identified' as a problem for 'Why Johnny Can't Sit Still'. The lucky kids are the few who still have fairly rural lives and can go out and play... burn off their normal energy. We are seriously messing up young men with the Modern lifestyle, even if it's 'cushier' than it was before.