Homozygous

Homozygosity is the genetic state required for a cannabis cultivar to "breed true" — for offspring to reliably resemble their parents. When both alleles at a gene locus match (either both dominant AA or both recessive aa), the plant cannot segregate that trait in its offspring; every gamete it produces carries the same allele. A fully homozygous plant crossed with another fully homozygous plant of the same genotype will produce 100% identical offspring, generation after generation. This is the goal of strain stabilization: through 5-8 generations of selective inbreeding, breeders increase the percentage of homozygous loci until the population produces uniform offspring 95%+ of the time. Homozygous IBLs (inbred lines) are the parent stock used to produce commercial F1 hybrids — when two genetically distant homozygous parents are crossed, every F1 seed inherits one allele from each side, producing maximum heterozygosity and hybrid vigor. The trade-off is that homozygous plants themselves are typically less vigorous than heterozygous hybrids — extensive inbreeding can produce inbreeding depression with smaller plants, lower yields, and accumulated recessive defects. Skilled breeders manage this by maintaining multiple unrelated homozygous lines and using them as F1 hybrid parents rather than growing the IBLs as commercial flower. Homozygosity is also why landrace preservation matters — many landraces have been homozygous for thousands of years, carrying stable allele combinations adapted to specific climates that no modern breeder could recreate.