Punnett Square - GCSE Biology Definition

A Punnett Square is a simple genetic diagram used to predict the possible combinations of alleles that offspring might inherit from their parents. It is named after Reginald Punnett, the scientist who developed it. The grid shows how alleles from each parent combine to produce different genotypes in their children. Each parent’s alleles are written along the top and side of the square. By filling in the boxes, we can see all possible allele combinations in the offspring and work out the probability of certain traits appearing. Punnett Squares are especially useful for understanding how dominant and recessive alleles are inherited.