Regardless, that does not mean that selective genes can be 100% permanently ruled out of a strains genetic code with enough selective breeding.Please check out Barbara McClintock's very old (50 years plus) work on "jumping genes" or transposons in maize and bacteria (humans have them too!) which led to her Nobel prize.
Things certainly do "skip around." Dominant and recessive Punnett squares are great for nursery school... just not in the agricultural nursery.