>History and data from various European nations suggest that some immigrant groups aren't able to integrate with the host society after multiple generations, and remain ghettoized with low employment and high crime rates (vastly higher than the native population, for certain categories of crime).

Twice as many Britons joined ISIS as served in the British military. <https://www.newsweek.com/twice-many-british-muslims-fighting...> The new ISIS members are not first-generation recent arrivals; they are the children and grandchildren of those who arrived decades ago.