As a child more or less clearly physically resembles parents, looking like somewhat of a synthesis of the physical characters of both parents, also psychically there may be some interesting signs of resemblance, in spite of our ironic saying "intelligent dad, dumb son!"
When people's behaviour tells something of the environment, of the culture, in which those people have been born and have been directed to some unfolding,
on the immediate surface it will look as if behaviour, thoughts and feelings are genetically and culturally predisposed, as if we were the robots of our own culture, the clear bearers and furtherers of the characters of the tribe or society that generated us.
Obviously nurture has a great importance in the development of behaviour, of thoughts and of feelings. A child that is physically well-nurtured and very well helped to unfold, to become psychosomatically cleverer, that child will appear to be more intelligent than other children that did not have a good nurture (good food, good shelter, love) and a good intellectual stimulation.
There are some people who by nature were predisposed for more intelligence, for a more glowing unfolding of their inner qualities, for greater things. But when such people will not be properly nurtured or psychologically supported, they may end up showing signs of psychic unbalance, they may even end up behaving as if mentally disturbed, sort of more irrationally behaving, tending towards criminal behaviour. If they had been given chances of unfolding in the ways of their predisposition, of their intellectual qualities, of their dreamy talents, they might have become great glowingly good personalities. For example one like Hitler might have become a great painter if his wishes of doing art had been corroborated or promoted in his environment. He did not, he was rejected, therefore he may have nourished a lot of resentment and may have ended up, as he did, making his the power of his personality weighing greatly in the world in the way that we know, very different from that of a famous painter.
Thus, a genetic predisposition, a considerate support, the fortune of having been born within a supporting environment, and also some good degree of astute and resolute willpower, with a will to ardently try and ever proudly unfold in spite of all the dire impediments, all may contribute to the particular actual lay-out of a personality.