Many years ago an old "linebreeder" told me the true genetic level is like a calm level of water, the averages of a population. Back when I was measuring the distributions of an average, of course for every individual above average there is another below average. Heterosis/hybrid vigor is like the crests of a wave that will return to the calm level, a non additive situation which was further established by MARC research experiments. The difficulty is being satisfied with the true "level", the tendency is to either ride the waves in choppy seas or add more "water"
"Hybrid vigor is like 2 + 2 = 5. It is as close to a free lunch as you will find in the cow-calf business. Allow me to provide another analogy. Breeding Angus to Angus is like depositing money into a checking account. What you put in is exactly what you will be able to take out. In contrast, breeding Angus to Hereford is like depositing money into a savings account. When you withdraw your money from a savings account you will take out more money than you deposited - because of the interest your money earned."
"Hybrid vigor is like a smoothing out of the damage which is
done by inbreeding. It's a genome wide phenomena which is
like a shot in the arm, an amelioration of the detrimental
effects of prolonged inbreeding/purebreeding."
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.