It took several decades before they fully settled down and bridged the achievement gap with WASP Americans. But bridged it was. By the 1950's studies showed Irish-Americans at the high end of the economic spectrum. The Old Country hasn't done so badly either (despite having the most useless political class imaginable). Ireland has been continually in the top five of nearly 150 countries as judged by the multi-faceted Human Development Index. Contrast that with the position of America's blacks. After half a century and trillions, yes, trillions of dollars spent trying to 'bridge the achievement gap' between blacks and Whites the gap today remains as wide as ever. Meanwhile blacks' ancestral homelands are without exception poverty-stricken hell-holes which are getting worse rather than better. Despite an avalanche of Western aid.
Even a sociology professor should be able to understand what's happening. After all Plato cottoned on to it 2,500 years ago, observing "this City is what it is because our citizens are what they are." And that's why in general (there will of course be exceptions) blacks and mestizos never will bridge the achievement gap. At least in the foreseeable future. But understand that even high-achieving Asian immigrants represent, at best, a double-edged sword. Highly tribal and nepotistic, they'll act like the cuckoo in the White nest, gradually pushing Whites towards the edge until they finally plummet to earth. Hell, they're doing it already. Just check out what's happening to White students at the Ivy League colleges. They're a minority, and a declining minority at that.