Complex sentence: He almost never allowed Genie's mother or brother to speak, and viciously beat them if he heard them talking without permission; any conversations they had were therefore always very quiet and out of Genie's earshot.
Split into simpler sentences: He almost never allowed Genie's mother or brother to speak, and viciously beat them if he heard them talking without permission. Any conversations they had were therefore always very quiet and out of Genie's earshot.