Mendel's second law shows how these are distributed. Independent assortment guarantees that no two eggs or sperm are alike. Miscegenation of whites with blacks produces several shades of brown skin color. Why biologists do not usually use the term race. The dynamic state of skin color and other features that constitute what some call race.
Race is a cultural concept.
Bell curves result from random breeding of beans in a field. The consequences of selection and inbreeding on a polygenic trait. Genius is difficult to define and measure. IQ scores may not be useful in predicting those geniuses who become eminent. How the eugenics movement led to social evils.