Both Tsarnaev brothers were culturally assimilated. Tamerlan was from an Americanized, mostly secular family, minor boxing celebrity in Boston, permanent resident, listened to American music, dated American women, celebrated American holidays. He didn't become "devout" for 6 years after moving to the US and "fanatical" two years after that. Dzhokhar immigrated even younger (approximately the same age as I was) and was a "typical" American kid by most standards. Maybe you have a different definition of "assimilation". My point is that superficial cultural assimilation is not always enough. It also has nothing to do with taxes.