Your anecdote gives me exactly the opposite conclusion; your immune
system was underdeveloped because your early diet was insufficiently
diverse. Your body only had to deal with the microbes in your yard,
so it never developed antobodies for other common bacteria in food.
When you encountered many such foods all at once, naturally you
became sick.
Our health would not be improved by similarly limiting our diets to
what we grew (nor would the financial disadvantage of such a wasteful
practice be without health consequences). /Your/ health would have
been much more robust if your diet had been more varied as a child.
Children who travel a lot, in particular, have strong immune systems
from having experienced the marvellous variety of bugs our planet
has to offer.
-- Lee Daniel Crocker <lee@piclab.com> <http://www.piclab.com/lcrocker.html> "All inventions or works of authorship original to me, herein and past, are placed irrevocably in the public domain, and may be used or modified for any purpose, without permission, attribution, or notification."--LDC