-Proposed by Mendel

-States that during gamete formation, the alleles of a gene segregate (separate) from each other and randomly unite with the alleles of the other parent during fertilization, resulting in genetic variation in offspring.

-Offspring inherit one allele for each gene from each parent through the random fusion of gametes during fertilization.

-Thus, the offspring will have a unique combination of alleles inherited from both parents, leading to genetic diversity and the possibility of different phenotypes.