Complex sentence: His mother, Emilie Preiswerk, was born into a family that regularly practised Spiritualism, the daughter of a man who held weekly seances with his dead first wife who instructed young Emilie to stand behind his chair to discourage ghosts.
Split into simpler sentences: His mother, Emilie Preiswerk, was born into a family that regularly practised Spiritualism. The daughter of a man who held weekly seances with his dead first wife who instructed young Emilie to stand behind his chair to discourage ghosts.