His father, the Emperor Kobun who was out in the succession to the imperial throne against his maternal grandfather, the Emperor Tenmu, committed suicide, and his mother, Hochi no Himemiko also died young (There are theories saying she committed suicide or was assassinated.)
父弘文天皇は母方の祖父、天武天皇との皇位争いに敗れて自殺、母十市皇女も早世(自殺・暗殺説もある。）