Complex sentence: Day-Lewis was born in 1957 in Kensington, London, the second child of poet Cecil Day-Lewis and his second wife, actress Jill Balcon, and the third son of his father, who had been married before.
Split into simpler sentences: Day-Lewis was born in 1957 in Kensington, London, the second child of poet Cecil Day-Lewis, who had been married before and his second wife, actress Jill Balcon. Daniel was the third son of his father, who had been married before.