Irish immigrants started out from a culture, where the typical peasant was 1/2 to 1/4th as wealthy as the median pre-Civil War American Slave. There was a period of time when ethnic Irish political machines helped to place the party faithful into cozy government jobs. This was beneficial, up to a point. However, there is a point where such subgroup politics becomes so corrupt, the leaders of that group keep their people in deliberate isolation to maintain their power.
The IQs of many ethnic immigrant groups to the US can be shown to have increased after several generations. The Polish and Italian immigrant groups' IQs increased from 85 to over 100 over the 1st half of the 20th century. There seems to have been a reversal of such trends for African American communities starting in the 60's. There are also studies of the African American children of US armed forces personnel in Germany. Their IQs are the same as other children growing up in Germany. My conclusion is that the leadership of the African American community and the influence of the US political Left, by glorifying a toxic subset of their ethnic culture, is holding the group back, in cultural isolation, in such a way as to harm the prospects of their children as strongly as lead in the water of Flint Michigan.
