Practice question

Gene interaction by definition requires contribution of at least two distinct genetic loci influencing same phenotypic trait; single gene governs monogenic trait without interaction, displaying dominance, incomplete dominance, or codominance. With two genes, possibilities for epistatic masking, complementation, additive effects emerge, generating modified dihybrid ratios like 9:7, 12:3:1, 15:1, 13:3. Minimum two genes produce four gamete types and sixteen F2 combinations necessary to detect interaction patterns experimentally. Adding third or more loci increases complexity toward polygenic networks, but fundamental concept remains pairwise non-allelic interaction observable in dihybrid cross analysis.