Complex sentence: Born "Gordon Langley Hall", Simmons' first decades were lived as a male, and as a young adult, was adopted by Margaret Rutherford, who was the subject of a biography Simmons wrote in later years.
Split into simpler sentences: Born "Gordon Langley Hall", Simmons lived her first decades as a male. As a young adult, she was adopted by Margaret Rutherford, who was the subject of a biography Simmons wrote in later years.