It is imperative therefore that the child is immersed in an environment of adequate external stimulation that may lead to a developer education as a human being. By therefore be ruled out as the sole determining factor in the ontology of the child's biological development, but mark it at different times to mature. If it were otherwise, the differences between siblings would be only natural, because they come from the same parents, but their personalities ever to be developed in the same environment would be equal or nearly equal, and the reality is not so. Likewise, we should not ignore the influence of endogenous and exogenous factors may be positive but also negative. In the case of John, the environment in which was embedded: the family, with an unstructured environment, very aggressive and unstable, negatively influenced him causing the need to escape, no return, a completely unnatural environment for him and hostile at first instance. Although react by imitating what he had seen on previous occasions, the boy knew he could return to the tribe once the danger, but did not. And why not again? In my opinion, to enter a community living with monkeys (vervet), who rejected him but accepted him as one, playing the cop catches him, he preferred to stay there. It is at this moment, when he starts making the influence of endogenous and exogenous factors while in their new environment, having to adapt your body to the new food, climb trees (by imitation), s etc The influence a medium that was not his natural causes could be influential also in the delay in the development of skills specific to their species, for example, the development of the quality of language, reasoning, in the words of the author, sufre some mental retardation and their adoptive parents Paul and Molly, a the child is still shy and not talkative .