That's quite possible, I really don't know, but kids learn a huge amount by the time they're 3. They'll cue off adult behaviour, and you can very easily acciden

That's quite possible, I really don't know, but kids learn a huge amount by the time they're 3. They'll cue off adult behaviour, and you can very easily accidentally teach them really bad behavioural habits very early on. If the adults exhibit addictive behaviour or magnify the significance of indulgent behaviour then kids will start learning that from day 1. So sure individual biochemistry can make a big difference, but a child's basic personality is largely established by age 4. Those early years make a huge difference.