Complex sentence: His father was enrolled in the Public Health program at Harvard University, hence his being the only monarch to be born in the U.S. Bhumibol had an elder sister, Princess Galyani Vadhana, and an elder brother, Prince Ananda Mahidol.
Split into simpler sentences: His father was enrolled in the Public Health program at Harvard University, hence his unusual place of birth for a Thai monarch. He is the only monarch to be born in the U.S. Bhumibol had an elder sister, Princess Galyani Vadhana, and an elder brother, Prince Ananda Mahidol.