They've got blonde hair, blue eyes, and occupy a special place in heart of generations of schoolgirls from every corner of the globe. But for years, Barbie and Ken appear to have been hiding a guilty secret.

The popular all-American toys turn out to have been created by "a full-blown Seventies-style swinger" with "a manic need for sexual gratification," who based their design on his favourite adult dolls, according to a new book.