DNA that does nothing?
It seems that most of our DNA is dormant. It doesn’t encode for protein production. Some of this supposedly dormant DNA has recently been shown to have important functionality, but there still seems to be much more information present than is used.
Here’s an article on the debate over how much of our DNA is functional.
Here’s an article on gene sequences that appear to have come from other organisms, entering our genetic code through horizontal gene transfer.
Here’s an article on DNA sequences that have been written into our DNA by viruses, some of which might still be capable of making us sick.