After the Kamakura period, due to the regulations governing the titles of Princes by Imperial Order, it was often seen for a member of the Imperial family, who was in his second generation or earlier, and not entitled to the throne, to became an adopted son of an Emperor or retired Emperor and then succeed to the throne, this example was called 'Seshu Shinnoke' (the Hereditary Imperial family) in future generations.
鎌倉時代以降、親王宣下の制度により、本来その資格のない2世王以下の皇族が天皇・太上天皇の養子・猶子となって親王の称号を世襲する例が散見されるようになり、これを後世「世襲親王家」と呼んでいる。