A person is a process, not a fixed object. Thinking that you can change a human being by changing their DNA is like thinking that you can reorganise a library just by changing the catalogue
Or - to put it another way - thinking that you can fully describe a human being by transcribing their genome is like thinking you can fully describe a phone system with a telephone directory. It’s the connections between phones & the contents of the messages between them which are important. And just when you think you are getting to grips with the system, someone invents the mobile phone & increases the complexity manyfold