Polygenic Inheritance

Polygenic inheritance describes traits controlled by multiple genes rather than a single locus, creating continuous variation rather than discrete phenotypes. In cannabis breeding, most commercially relevant traits—plant height, flowering time, cannabinoid ratios, and terpene profiles—are polygenic. This means offspring phenotypes exist on a spectrum, and selecting for desired characteristics requires multiple generations and careful tracking of parent genotypes. Breeders working with polygenic traits must account for gene interactions, environmental influence on expression, and the unpredictability of trait combinations in F1 and F2 generations. Understanding polygenic inheritance is foundational to modern cannabis breeding programs seeking stable, uniform cultivars.

Breeders leverage polygenic inheritance by backcrossing selected parents over multiple generations to concentrate favorable alleles and stabilize desired trait combinations. Genomic selection and marker-assisted breeding increasingly allow breeders to identify and track polygenic contributors earlier, accelerating stabilization of commercial lines while reducing field trial cycles.