actually there is truth into this. Scientists have been doing alot of research on anger, and studying mono, di-twins, and found African American children are angered much easier. Also has to do with diets, which they can't control, so it's flawed, since A.A. they study had lower incomes, and did not eat the same amounts of tryptophan which plays a role in serotonin release, so that could account for their mood swings.
I rarely agree with anything you say, because I find most of it to be pure BS, but I'm willing to concede there might be some credence to the theory that diet is a strong mitigating factor in a person's temperament (regardless of race or ethnicity)
There are certain herbs that have an amazing tonic effect on the entire nervous system. I find that when I stick to a strict vegan diet, I'm much more serene. Throw some eggs, or god forbid bacon or sausage in there and I'm a tightly wound bag of nerves. The more chemical additives in the food, the more mood swings I'm susceptible to.
I've become so sensitive to it, I can even tell if I've eaten something mistakenly based simply on how I'm feeling afterwards, ...physically, mentally & emotionally..