Dou Wei
Dou Dexuan was born in 598, during the reign of Emperor Wen of Sui. His family had been a hereditary aristocratic family during Sui and its predecessor dynasties Northern Zhou and Western Wei, and his grandfather Dou Zhao (竇照) had married a daughter of Western Wei's paramount general and ancestor to Northern Zhou's imperial house, Yuwen Tai, who was later known as Princess Yiyang during Northern Zhou, and he was created the Duke of Julu. Dou Dexuan's father Dou Yan (竇彥) inherited the title and served as a commandery governor during Sui. His older brother Dou Deming (竇德明) served on the staff of Emperor Taizong of Tang while he was the Prince of Qin. His granduncle Dou Wei was chancellor during the reign of Emperor Taizong's father and Tang's founder Emperor Gaozu.