What shapes intellect?

Research takes a step forward with every finding that intellectual ability need not depend on heredity. But individuals have to be no less alert to alternative theories that could limit their freedom of thought as surely as the acceptance of political tyranny. Here is a challenge beyond the current controversy over the ''Profile of American Youth'' commissioned by the Pentagon from University of Chicago researchers.

The study of almost 12,000 young men and women had been seized on to support racial genetic theories when black and Hispanic participants got lower average scores than whites on an armed services vocational aptitude test. Now Chicago researchers have countered the heredity assumptions by attributing the differences to the ethnic minorities' ''cultural isolation'' and social and educational disadvantages.

One of the researchers reportedly suggested that tests like the armed services test favor aptitudes and skills learned in the prevailing white culture. Another generalized that one's human mind is the result of experience, of ''everything that the culture you live in has put into it.'' He went so far as to say that ''it's not your own personal mind; it is your piece of the communal mind - the words, the mathematical tools, the habits, the diagrams of your culture.''

By this reasoning, society - from the family to the federal government - ought to be aware of the cultural climate it provides. It should offer susceptible intellects the highest standards of thought, education, morality. It should recognize the potential influence of bad examples, of wrong information, of harmful attitudes.

At the same time, here is reason for the individual to guard against susceptibility to the lower standards so blatantly displayed right now. No one's intellect has to be a prisoner of circumstance any more than of heredity. No one's intellect has to be a ''piece of the communal mind.''