Allelic Fixation

Allelic fixation refers to a genetic state where a particular allele (variant form of a gene) exists in a population at 100% frequency, meaning all individuals carry identical copies at that locus. In cannabis breeding, fixation is a key objective when stabilizing desired traits—breeders work across multiple generations to lock in specific characteristics like flower color, growth structure, or terpene profiles. Once a trait reaches fixation, offspring reliably express that phenotype without segregation. This concept is foundational to creating true-breeding or 'IBL' (inbred line) cultivars. Fixation differs from dominance; a fixed allele persists regardless of whether it's dominant or recessive, simply because it's the only version present in the breeding population.

Breeders pursuing allelic fixation typically employ selective breeding protocols over 6+ generations, backcrossing or selfing to eliminate heterozygosity. Achieving fixation allows cultivar stability, predictable seed production, and reproducible commercial harvests across grows and regions.