[CuriouslyC]

An IQ of 60 isn't difference, it's indicative of either malnutrition, severe neglect, or some form of developmental disorder. In fact, I'd be surprised if there are many people of below average intelligence that don't suffer from one of those things. I'd even wager that if you took any random infant that didn't have a developmental problem and raised them in a loving affluent western family with good food and an enriched environment odds are good their IQ would measure >110 after a few years.

[Retric]

That's your own bias talking, genetics and environmental toxins can both cause significant issues. But, so can non genetic birth defects resulting from disease or what amounts to bad luck.

Further sub 110 IQ's don't indicate a problem. Natural variation is simply much wider than you assume.