Complex sentence: Growing up in the East End, Aaronson was one of a group of friends today generally referred to as the Whitechapel Boys, all of whom were children of Jewish immigrants and shared literary and artistic ambitions.
Split into simpler sentences: Growing up in East End, Aaronson was part of a group of friends today generally referred to as the Whitechapel Boys. The friends where all children of Jewish immigrants and shared literary and artistic ambitions.