In ancient times, there were many opinions on naming. According to current standards, the surname is basically that of the father. Qin Shihuang's name is Ying Zheng, so his son should also be named Ying. But in ancient times, there was no such thing. It is so rigid and there are not so many rules. The name was originally created for identification. In ancient times, there may not be great requirements for surnames. As long as it has its own characteristics, others can identify it.
For example. Ying Zheng, this surname had never appeared before Qin Shihuang, but Qin Shihuang named himself Ying Zheng, and named his sons Fusu and Hu Hai. In ancient times, we also know that the emperor's power is very powerful. Since everyone has exported it, the ministers have no choice but to abide by it. So much so that no one has thought specifically about this issue until now.
Another main reason is that rules are man-made and are not permanently fixed. In other words, they can be changed. So in ancient times, there must have been people who made rules specifically, but we all know In ancient times, it was basically an autocratic monarchy. The monarch had the greatest power. The same was true for Qin Shihuang. He had great achievements in history, but he was also a famous tyrant. Anyone who did not obey his instructions would be punished. Certain penalties may even result in loss of life.
From this point of view, Qin Shihuang’s decision can be regarded as a rule, and no one will dare to refute it. All in all, Fusu and Hu Hai both had the surname Ying. However, in ancient times, it was not customary to call them by their surnames. Until now, when they are called by their names, they naturally do not use their surnames.