Homozygous Heterozygous

Homozygous and heterozygous refer to the genetic condition of allele pairs at a given locus. A plant is homozygous when both alleles for a trait are identical (e.g., AA or aa); heterozygous when alleles differ (Aa). In cannabis breeding, understanding these states is critical for predicting offspring phenotypes and stabilizing desired traits across generations. Homozygous lines breed true for specific characteristics, while heterozygous plants may segregate multiple phenotypes in their progeny. Breeders use test crosses and repeated selfing to identify homozygous individuals and establish stable cultivars.

Breeders intentionally work toward homozygosity in critical traits—cannabinoid profiles, flowering time, structure—to create stable F1 hybrids and inbred lines. Understanding zygosity helps predict whether a desirable phenotype will reliably pass to offspring or risk segregating away.