// Definition
The phenomenon where offspring of genetically dissimilar parents exhibit enhanced vigor, size, fertility, and overall performance compared to either parent. In cannabis breeding, this produced the exceptional F1 hybrids of the 1990s golden era.
// From the Episode
Kevin Jodrey explained that 1990s breeders were crossing genetically distant lines (landraces from different continents) producing dramatic hybrid vigor. As gene pools narrowed through modern breeding focused on a few popular lines (Z hybrids), heterosis diminished. The result: 'a hundred of them but fundamentally they're all pretty similar.'