Other forms: Punnett squares
In genetics, a Punnett square is a simple chart that's used to predict what genotypes (genetic makeup) and resulting phenotypes (observable physical traits) that parents might pass on to their offspring.
Named for its inventor, British geneticist Reginald Punnett, a Punnett square lays out all possible genetic outcomes of a breeding experiment. For a single trait, it's usually a grid of four boxes, 2x2, that pairs up alleles—the different versions of a gene inherited from each parent. Capital letters represent dominant alleles, and lowercase letters represent recessive ones. Placing one parent's alleles along the top and the other's along the side allows you to fill in the grid, making it easy to calculate the probability of offspring inheriting specific traits.