Only about 100 out of 20,000 human genes are deterministic, meaning they guarantee a specific disease if mutated.

“there's only about 75 to 100 gene so there's 20 them just for the listener there's about 20,000 genes in the human genome directionally only 100 are deterministic polygenic single gene leads to problems so you have the mutation for cystic fibrosis you are getting cystic fibrosis you have the gene for this glycogen storage disease you are getting it virtually every disease that we think of commonly of course does not have a deterministic genome”