Yes, you can write your own tutor for your doctoral thesis, but you need to follow some principles. First of all, the doctoral thesis needs to choose the potential research direction that it can grasp and control, and open up new research fields. Secondly, the doctoral thesis needs to evaluate one's tutor objectively, fairly and comprehensively to avoid exaggerating or distorting the facts. Finally, the doctoral thesis needs to avoid infringing on the privacy of the tutor and not revealing any unauthorized information.