"A torrent of government investment has improved the buraku* so they are no longer slums. Yet average income for buraku families is still only about 60 percent of the national average, and social problems are proving to be far more persistent than discrimination. Buraku leaders acknowledge that alcoholism is a disproportionate problem in their communities. Poverty and alcohol, in turn, weaken the family in the buraku. Single parents are almost twice as common in the buraku as in the nation as a whole. Five percent of burakumin are on welfare, seven times the rate in the overall population.
A 35-year-old study in Japan found that buraku children had lower I.Q.'s than non-buraku children in the same public schools.
http://query.nytimes.com/gst/fullpage.html?res=9B01E7DB1139F933A05752C1A963958260&sec=&spon=&pagewanted=1 The kicker is that buraku seem to do just as well as regular "ippan" Japanese when they immigrate to the US. Thus it seems that pervasive deficits in income, health, IQ, etc. can be caused by culture, environment, and (conscious or unconscious) prejudice, with no innate genetic explanation required.
http://matthewyglesias.theatlantic.com/archives/2007/11/buraku.php *I remember reading in James Clavell's novel Shogun about 1600's-era Japanese prejudice against the "Eta", who worked at dirty jobs, had different eating and living habits, and were shunned by regular Japanese. Buraku is apparently a less offensive term for the same group.