Earlier quoted context omitted.
How about a correlation between IQ and race. It seems that no one will touch the subject out of fear the it would end their career.
What's the use about a study on _correlation_ between these two things? You could also have a study on correlation between IQ and poverty, IQ and access to education... Not to mention, what's the point of IQ anyway? Maybe no one is picking up the subject because it would be a waste of time?
Understanding correlation is the first step to understanding causation, and a statistically significant correlation, by definition, implies that it is unlikely that there is not a causal relationship, though the cause may not be directly between the two studied variables.
> You could also have a study on correlation between IQ and poverty, IQ and access to education...
You could and you do. Or (to pick a real example that came up near the top, by recency, of a Google Scholar search for race and IQ) of the correlations between IQ, sex, and maternal obesity, controlling for (among other factors), race differences in IQ, which requires first having studied the correlation between race and IQ.
> Maybe no one is picking up the subject because it would be a waste of time?
Maybe the story that no one is picking up the subject is just a lie easily refuted by searching Google Scholar.