Your adult height depends on your childhood nutrition, so if childhood nutrition can affect your height does that mean it also affects your brain development?
So would shorter/smaller people have brains that are less well developed?
Some people are short just because of genetics, and they wouldn’t have a lower IQ on average just because of their height.
However, malnutrition does affect IQ, so if they are short because they were malnourished, then they are likely to score lower on IQ tests and other tests of cognitive brain function. If someone is malnourished consistently during their developmental years, the effects on their brain functions are permanent. Good nutrition later will not undo the effects of malnutrition during their developmental years.
Malnutrition during developmental years can also cause anti-social behavior, but I personally haven’t read anything to indicate whether this is a separate effect (i.e. purely or significantly chemical) or if it is just a result of social pressures caused by their peers reacting to their lower intelligence.