An interesting analogy but slightly flawed in terms of looking at genomes of already viable organisms. A person whose genome is sequenced to compare to the reference has already undergone the selection criteria for viability and development. Basically, there are plenty of sites where single mutations would lead to a complete breakdown of making a "human" but those would never be seen in a sequenced genome.

The other main difference is that of course code is written to be concise and concrete. As far as I know, no one pastes in some random code that doesn't perform a function just in case it may be needed in the future. Of course, biology works precisely in that way and the genome is a mess of evolutionary history with plenty of space for modification without really resulting in any functional change. So a better example of those 0.6% may be that you can have typos in the comments of the code. In fact, for any large piece of software, I would be surprised if the comment section did not contain at least 0.5% typos.