Practice question

Classical analysis of gene interaction assumes loci unlinked, assorting independently, exhibiting complete dominance individually, so 9:3:3:1 serves as theoretical reference expectation for two genes. Deviations then attributed to inter-locus epistasis rather than linkage distorting gamete frequencies. Linkage would confound interpretation by producing parental excess and altering 1:1:1:1 gamete ratio, mimicking interaction. Assuming independence isolates masking effects, permitting classification into dominant 12:3:1, recessive 9:3:4, duplicate dominant 15:1, complementary 9:7, suppression 13:3 types based solely on how phenotypic classes combine from four basic classes.