Who commits suicide?

In one of the largest studies on suicide ever conducted, researchers found that men with especially low scores on intelligence tests are two to three times more likely than others to kill themselves. Men with low IQ scores and only a primary education were no more likely to kill themselves than men with high IQ scores and a higher level of education. But men with low IQ scores and higher education were at a greater risk of suicide. And men with low IQ scores and highly educated parents were at the highest risk of all.

Could the problem be the high expectations of parents?  Or is this proxying for some other relevant variable?  Here is the story.