Complex sentence: Society demands the secrets of their extended life spans, refusing to believe that the Howard Families simply chose their ancestors wisely, and when the Howard Families fail to produce any such techniques, the Families are persecuted and interned.
Split into simpler sentences: Society demands the secrets of their extended life spans, refusing to believe that the Howard Families simply chose their ancestors wisely. When the Howard Families fail to produce any such techniques, the Families are persecuted and interned.