Complex sentence: Her parents were both teenagers when she was born; though reticent in public about this aspect of her childhood, she was estranged from Monasterio and has claimed that no father is listed on her birth certificate.
Split into simpler sentences: Her parents were both teenagers when she was born. Chastain is reluctant to publicly discuss this aspect of her childhood; she was estranged from Monasterio and has said that no father is listed on her birth certificate.