<em>For a dihybrid cross in which the two genes concerned obey simple dominant/recessive law and are independently assorting, </em><em>four phenotypes are produced in the ratio 9:3:3:1. </em>
The dominant gene takes up the largest ratio (9/16) while the recessive gene takes up the smallest (1/16). Any deviation from 9:3:3:1 and the number of phenotypes produced from a dihybrid cross is an indication that the genes involved do not obey Mendelian laws.