Complex sentence: His mother's father emigrated from Vienna, and her mother, Bertha Sykes Miller, was born in New York City into one of the early English-Jewish families to have settled the United States in the mid- 17th Century.
Split into simpler sentences: His mother's father emigrated from Vienna, and her mother was born in New York City. Her mother Bertha Sykes Miller came from one of the early English-Jewish families to settle the United States in the mid 17th Century.