It seems that the cause of aging is damage to DNA, either from telomere shortening, mutation from oxidative and metabolic stress, and maybe programmed methylation over time. I'm thinking one solution would be to copy a young person's DNA, store it stably, and as they grow older, genetically engineer them to have their youthful DNA, reverting organ damage as the healthy new cells proliferate. How could this be done, what issues could arise?