The number of useful ways of assembling nucleic acids is stupifyingly large. It's probably larger than the total number of atoms in the universe. This means that the number of possible kinds of human beings is vastly greater than the number of human beings that has ever lived. This untapped potential of the human species is immense. There must be ways of putting nucleic acids together which will function far better - by any criterion you wish to choose - than the hereditary instructions of any human being who has ever lived. Fortunately we do not know, or at least do not yet know, how to assemble alternative sequences of nucleotides to make alternative kinds of human beings. But in the future we might well be able to put nucleotides together in any desired sequence to produce whatever human characteristics we think desirable. A disquieting and awesome prospect.