I think it makes them fatter too
Correlation does not indicate causation.
Poor kids will come from parents with genes that are predisposed to low intelligence. Then they receive little to no early stimulation. Then they get low quality food.
And these overly simplistic morons say 1 factor is to blame. Not the fact that they come from low class backgrounds. Not the fact that kids at age 3 who eat fast food come from parents with low IQ. Not the fact that these kids get little to no early stimulation and are plunked in front of the TV all day watching the idiocy these morons spew out. NOOOOO. It is only because of the food.
TV is the junk food of intellectual stimulation. This is like the pot calling the kettle black. And then implying it is only the kettle who could be black.
Question: "Processed foods making your kids dumb?"
Answer: "No, your kids were already dumb to begin with."
that is the inconvenient truth
We don't actually know the genes responsible for IQ, but it's safe to assume there is a combination of genetic and environmental factors that determine one's IQ. Despite the wishful thinking by IQ denialists such as Gladwell, I would estimate the former plays a bigger role than the later. Evidence of this is that the macroscopic appearance of the brain of higher IQ individuals is actually different than that of average or dull people, which cannot be readily accounted for by nurture. Or that identical twins separated have similar IQs, despite different environments. The good news is IQ isn't completely hereditary, or we could theoretically have an idiocy type scenario.
Regardless of whether IQ is an indicator of all around intelligence, eating shitty processed food will affect your brain performance and make you slower. There's a lot of research linking what you eat with how your brain functions. Certain foods will inflame your brain and give you brain fog.
The Ultramind Solution is probably the best book you can read to get an introduction to the connection between food and your mind.