I've been working on a piece about how humans effectively have hardened firmware, and gene therapies need to do A LOT to try to get around the various defenses our bodies evolved. I should probably finish that article...
Imagine if random DNA really could just float in and out of the blood streams genetics? We'd be constantly battling random protein production and weird abnormal stuff.
If the institutions of science and technology lasted thousands of years evolution would prefer people with the less hardened firmware, as in, the ones to survive and pass their genes would be the ones with the most "hackable" genes.