in my limited experience and understanding young people are influenced by their surroundings more than are by the surroundings of others. The more abstract notions of geneology, origin, and cultural identity radiate from the first (current surroundings) and are interpreted through the lens of the first.
IF, current surroundings are unpleasant (perceived), unfair (perceived), unwelcoming (perceived), and so on THEN one looks over the fence to other surroundings and then begins to build fantasy (or abstractions of current circumstances through externally modified lenses). There may well be cases were all is well with one who is otherwise perfectly happy and upon reports of things about which they are told they are related ... they then turn to the dark side ... but generally, current reality determines proclivity to the dark side, not new knowledge indicating bad things to relatives elsewhere. If one has already embraced their current surroundings they are inclined to use their current surroundings to effect change within the guidance of their current surrounding. If one has not embraced their current surroundings, then external events and surroundings provide the landscape to construct fantasy.
Take home message ... while these folks may have been in the US for some time, their experience has not been a happy on. This may be from indoctrination, personal experience, or illness ... but this is the work of unhappy people.
DS, on the obvious.