It seems obvious to me that the kind of pressure to which you are referring is not limited to family. It would be easy enough to threaten a high school boyfriend. Or the family of your child's former best friend. Or a former co-worker. Or any friend. Or even a complete stranger.

Extortion can be effective well outside family lines.

And, of course, extortion is equally effective on USians, Brits, Indians, Nigerians, or anybody else.