According to the Biography of Lv Buwei, this was planned by him early in the morning. Although he was a wealthy family, he wanted status and power in ancient times, so he was far from satisfied with these, so he went to six countries and planned a long-standing overall situation. Evonne is one of his chess pieces. She was originally a gift from Lv Buwei to Zi Chu, but before giving it to him, he had already had sex with Evonne and recorded Evonne's pregnancy, so that his son could be born and inherit the throne. Unofficial history has relevant records, which are well-founded, but first of all, its credibility is in doubt.
According to the biographical records of Qin Shihuang, Evonne was a noble family, not a prostitute. In this case, how could he marry a businessman first and then marry Zi Chu? Besides, where did Lv Buwei come from? He said that Zhao Haoqi of the State of Qin would pass on his position to Zi Chu and then to his grandson? And ten thousand steps back, even if Evonne was pregnant before entering the palace, it should be a delivery shortly after entering the palace. This Zi Chu is not a fool, and he knows it. However, according to the birth date of Qin Shihuang, it is obvious that she was pregnant after entering the palace.
As for why unofficial history always said that Qin Shihuang was the son of Lv Buwei, firstly, there were too many people who wanted to overthrow the rule of the Qin Dynasty, which created reasons for those who wanted to rebel. Secondly, Lv Buwei planned to win the support of Qin Shihuang through the love between father and son. But what happened in the middle, whether he was an illegitimate child, we have no way of knowing, and we can only leave it to future generations for infinite speculation.