Passage: Ribal al-Assad was born in Damascus, the 13th of 16 siblings. He is the son of Rifaat al-Assad and his third wife Line Al-Khayer, sister in law of the late Saudi king Abdullah bin Abdulaziz, and is thus a member of the al-Assad family. His father, Rifaat al-Assad, a younger brother of the late President Hafez Al-Assad, was a powerful security chief and commander of the Defense Companies, who was responsible for the 1982 Hama massacre. After attempting a coup d'état, he and his family went into exile in France, then the UK. Ribal, at the age of 9, and his family then moved to Paris, where he continued to live until the age of 16. At the age of 16, Ribal al-Assad began High School in New York and Houston, before attending university in Boston.

Question: How man siblings did Ribal al-Assad have?
16