[GeronL]

Taejong executed or exiled many of his supporters who helped him ascend on the throne in order to strengthen the royal authority. To limit influence of in-laws, he also killed all four brothers of his Queen Won-gyeong and his son Sejong's in-laws. Taejong remains a controversial figure who killed many of his rivals (including Jeong Mong-ju and Jeong Do-jeon) and relatives to gain power and yet ruled effectively to improve the populace's lives

[Impy]

Well, what married man hasn’t wanted to kill his in-laws huh? ;d

Byzantine Empress Irene had her own son’s eyes gouged out (he died). They were way into political mutilation, usually blinding. Contrast her contemporary Charlemagne who merely had his rivals forcibly tonsured and confined to monasteries.