Complex sentence: Erik, a chemical engineer; and Ernest, a lawyer, who, like Niel's brother Harald, became an Olympic athlete, and played field hockey for Denmark at the 1948 Summer Olympics in London.
Split into simpler sentences: Erik, a chemical engineer; and Ernest, a lawyer. Like Niels's brother Harald, Ernest Bohr became an Olympic athlete, playing field hockey for Denmark at the 1948 Summer Olympics in London.