Homozygous Heterozygous

Homozygous and heterozygous refer to the genetic composition of an organism at specific loci. A homozygous plant carries two identical alleles for a trait (e.g., AA or aa), while a heterozygous plant carries two different alleles (e.g., Aa). In cannabis breeding, understanding these states is fundamental to predicting offspring traits and stabilizing desirable characteristics across generations. Homozygous lines breed true for their expressed traits, making them valuable for creating stable cultivars. Heterozygous plants may exhibit hybrid vigor but produce variable offspring, requiring careful selection to fix desired traits into homozygous form.

Breeders intentionally work toward homozygosity in stable lines through repeated self-pollination or inbreeding, stabilizing phenotypes like cannabinoid profiles, terpene expression, and plant structure. Conversely, F1 hybrids are often heterozygous crosses between two homozygous parents, prized for consistency and vigor in commercial seed production.