If an auto is crossed with a pure photo, 100% will be photo, but a percent will carry the auto recessive gene, meaning if they are bred together, some of the offspring will be auto. Also herm tendencies are 100% genetic and passed along from parents to siblings. That doesnt mean that there is a 100% chance the siblings will be herm, but at least a percentage will carry that trait. Even plants that herm due to stress carry that trait, some plants will not herm, no matter how much you abuse them, while others do, this is also genetic.