We study the appearance of genetic information starting from a system where self-reproductive and enzymatic functions are supported by the same sort of molecules. In a first phase, the information must have arisen in the form of rate independent sequences as records of enzymatic functions. Although this stage must have played an important role in evolution, it will be shown how its evolutive capacities were blocked by the impossibility of appearance of geno/phenotype duality. Finally, a logical scheme is proposed for (...) a transition process toward a system with a code offering a simplification of the conditions required from the assumption of a maximum use of the double RNA capacity, both reproductive and enzymatic. (shrink)