Urgh, headline sucks! Does the study really find that being poor causes a limiting of mental ability? Or does being poor correlate with a limiting of mental a

Urgh, headline sucks! Does the study really find that being poor causes a limiting of mental ability? Or does being poor correlate with a limiting of mental ability? My take is that bad nurturing causes the decline in mental ability, and wealth is merely a reasonable indicator for quality of nurturing. This distinction is important if attempts are made to mitigate the limitations.