Gregor Mendel was attributed for discovering the principles that governs heredity. He performed experiments and observed the results in order to come up with this principles. One of these principles, which he called Law of Independent assortment, was discovered when he performed an experimental cross on pea plants using two observable traits i.e. dihybrid cross because it involved two genes encoding each trait.
In his law of independent assortment, he stated that a pair of allele of one gene separated into gametes independently of the other pair of allele for another gene. This means that the separation of the two alleles in a gene does not affect the separation of alleles in the other gene. Mendel got a phenotypic ratio of 9:3:3:1 when he performed the dihybrid cross, which is what one would normally expect if each allele get separated independently to produce four possible combination of gametes in each parent.
