IQ and Disease

As the sample started from age 11, you could also suggest that some good habits and preferences had been drilled into them, possibly in an environment that ensured their IQ was allowed to flourish without too many adverse impacts.  However, this can s o o easily drop into a bad nurture, etc. etc discussion that it probably needs far more specialist care in its management than many sloppy statistical studies receive.

That said it is not clear what benefits going forward can be extracted from the study in its present form. The base year of 1936 came after the depression years when diets and concentration on food issues was more likely, better nourished parents tend to produce better developed offspring. The war years saw great concentration of efforts on childhood nutrition and that might (hopefully?) have played a positive role in both their physical/mental development and in establishing a sound basis for progress. Maybe that conditioning helped to close some minds to the blandishments of the deep-fried Mars Bars and their ilk. It is a conversation starter rather than a problem solver. I did note that the pattern of childhood IQ being a useful predictor of life out turns has been a consistent factor across other studies, may I express muted, very muted surprise?