Complex sentence: Affluence in the United States has been attributed in many cases to inherited wealth amounting to "a substantial head start": in September 2012, the Institute for Policy Studies found that over 60 percent of the Forbes richest 400 Americans had grown up with substantial privilege.
Split into simpler sentences: Affluence in the United States has been attributed in many cases to inherited wealth that amounts to "a substantial head start". In September 2012, the Institute for Policy Studies found that over 60 percent of the Forbes richest 400 Americans had grown up with substantial privilege.