I attended a symposium titled _The Long Reach of Childhood Poverty_ at AAAS that featured the results of two studies correlating substantially the same message you see here. CAVEAT: No mention was made of crime nor impulsive behavior. High stress levels in early childhood - ie under 5 years - produce cortisol. If cortisol levels continue high, epigenetic changes happen and the child becomes loud, and overactive. Not impulsive. But the changes are permanent. One of the studies noted that a small additional income during early childhood reduces incidence of this and positively affects health, educational attainment, and lifetime earnings. This could come from the earned income credit or from tribal shares in the case of native americans.