What conclusion can we draw from the factors affecting intelligence?

Are some people born clever and others stupid?(1 7)To some extent our intelligence is given to us at birth, and no special education can make a genius out of a child born with low intelligence. On the other hand, a child who lives in a boring environment will develop his intelligence less than that who has rich and varied surroundings. Thus the limits of a person’s intelligence are fixed at birth, but whether one reaches those limits will depend on his environment. This view can be supported in a number of ways. It is easy to show that intelligence is something we are born with. If we take two unrelated people at random from the population, it is likely that their degree of intelligence will be completely different. If, on the other hand, we take two identical twins, they will very likely be as intelligent as each other. This clearly suggests intelligence depends on birth. Imagine now that we take two identical twins and put them in different environments.(18)We might send one, for example, to a university and the other to a factory where the work is boring. We would soon find differences in intelligence developing and this indicates that environment as well as birth plays a part. This conclusion is also supported by the fact that(19)people who live in close contact with each other, but are not related at all, are likely to have similar degrees of intelligence.