Complex sentence: She was born in Nairobi, Kenya and grew up in South Africa where she lived until 1956 becoming an anti-apartheid activist, when she moved to England, before eventually moving to the United States and becoming a U.S. citizen in 1972.
Split into simpler sentences: She was born in Nairobi, Kenya and grew up in South Africa where she became an anti-apartheid activist. In 1956, she moved to England, before eventually moving to the United States and becoming a U.S. citizen in 1972.