First of all, human pregnancy time is actually long and short.
According to Hanshu, Liu Fuling, the mother of Emperor Zhao Di of the Han Dynasty, was pregnant 14 months when she was pregnant with him. Although there was no B-ultrasound and urine test in Han Dynasty, pregnancy could not be diagnosed, but there was a complete sleep record. There should be enough evidence in the history books to prove that Liu Fuling was born in 1 1 month when her mother was pregnant. In other words, there are very few people who don't stay in their mother's womb for about 280 days. According to this situation, Qin Shihuang may have been born after a long period of standby. According to Records of Historical Records and Biography of Lv Buwei, Zhao Ji, the mother of Qin Shihuang, was originally the concubine of Lv Buwei, and was pregnant when she was betrothed to a stranger by Lv Buwei. Evonne concealed this fact, which involves many possibilities. Evonne found that her period was delayed, so she thought she was pregnant. It is also possible that Evonne has morning sickness or something like that, or Evonne is diagnosed as pregnant by a doctor. Another possibility is that Zhao Ji calculated that Qin Shihuang was the son of Lv Buwei, but she thought she was pregnant. There are many possibilities involved, that is, delaying Evonne's pregnancy for half a month to two months, which theoretically exists.
Secondly, although the ancients didn't understand DNA, they would also calculate whether they were biological children by appearance and pregnancy time.
So, of course, Lv Buwei doesn't know DNA, but they will also guess who Qin Shihuang is according to his appearance, personality and the time he spent in Evonne. If Qin Shihuang doesn't look like a stranger, strangers will doubt Qin Shihuang's lineage and won't make Qin Shihuang a prince at all. Since the barbarians made Qin Shihuang the crown prince, letting Qin Shihuang inherit the throne normally can only show that the barbarians don't doubt Qin Shihuang's bloodline at all. If strangers don't doubt Qin Shihuang's lineage, it at least shows that Qin Shihuang looks more like a stranger in appearance. From this perspective, perhaps Qin Shihuang was the son of an alien, but he was born prematurely.
In a word, Qin Shihuang had children of both Lv Buwei and aliens. I tend to think that Qin Shihuang is the biological son of aliens.