In one theory, it was due to his bad terms with Harunobu: Nobutora disliked his heir Harunobu (Shingen) and was partial to his second son Nobushige TAKEDA, and started to think about disinheritance.
信虎が嫡男の晴信（信玄）を疎んじ次男の武田信繁を偏愛しており、ついには廃嫡を考えるようになったという親子不和説がある。