You have trillions of cells, each that contain billions of bases. Each cell can go wrong in its own way, and what you have to patch it back to is different for

You have trillions of cells, each that contain billions of bases. Each cell can go wrong in its own way, and what you have to patch it back to is different for every person All of these steps are currently not possible: * establish a perfect sequence for an individual * find mutations non-destructively (ie cell survives) * send a specific edit to a specific cell in live animal * perform just that modification (see https://en.m.wikipedia.org/wiki/Off-target_genome_editing https://en.m.wikipedia.org/wiki/Off-target_genome_editing)