They are trying to instil as much of this culture into their children as possible. They do have constraints in a foreign land. Most of the time, changing of accent is automatic, sometimes necessacitated and only few times intentional to derogate our own culture. I for myself have kept my original Indian accent, it was my choice. But my children who grew up in a small town without Indian friends of their age group, developed US accent. They try their best to blend the two cultures and adopt what they feel is the best of the two. They are living in the present.