On the right is a Punnett Square set up with two independently segregating genes. It looks like a dihybrid cross but if the phenotyes were examined, this particular cross would produce a 1:4:6:4:1 ratio. This is a quantitative cross. The genes in question produce identical effects and are additive. Therefore, the square containing four capital letters displays the maximum phenotype while the square with four lower case letters displays the minimum. Heights, starch content of endosperm, skin coloration and many other characteristics are controlled by quantitative genes. Flip to the next card to see the spread of these quantitative genes. Remember, this is quantitative inheritance. A and B produce the same effect and are additive.