"Actually it tends to be the opposite. Immigrants arrive and create a pocket of criminal activity calld a Ghetto, and young nationals see this as a "cool" way of life. Leading to what winds up as these "chavs" in Paris."
Anyone that doubts this should try to find an alternative explanation for the majority of 'chavs' adopting an Afro-Carribbean "yardie" style of speaking, and in some cases fashion also. This applies to both anglo-asian and white chavs.