While Sima Qian's Records of the Grand Historian does not specify Ziying's age, it implies that he had at least two sons, whom he consulted.
Being Qin Er Shi's nephew
According to historian Professor Wang Liqun's analysis, the maximum possible age of Ziying when Zhao Gao assassinated Qin Er Shi was 19. Therefore, his sons would have probably been around the ages of 1–2, and hence it was not possible for him to consult them. For Ziying's sons to be old enough to be consulted, a traditional age for them should have been around 14–16. Them being 14–16 in 207 BC when their supposedly great-grandfather Qin Shi Huang, if he had been alive, could only have been 52 is highly improbable. It seems unlikely that Ziying was Fusu's son or any grandson of Qin Shi Huang.
Being Qin Er Shi's brother
Ziying being another elder brother of Huhai was as unlikely as a grandson of Qin Shi Huang. Since Huhai showed no restraints killing at least twenties of his siblings after ascending to the throne, sparing one elder brother is not impossible but rather incredible.
Being Qin Shi Huang's brother
Li Kaiyuan in his study stated that Qin Shi Huang only had three brothers of any kinds: one paternal half-brother and two maternal half-brothers, therefore Ziying, if indeed being another brother of his, would have had more mentions in Chengjiao's supposedly betrayal.
Being Qin Shi Huang's nephew
Ziying being Chengjiao's son bore no direct threats to Huhai's reign, being neither one of Qin Shi Huang's descendants nor in higher seniority in succession to Huhai. Ziying was also said to have tried to persuade Huhai to not killing Qin Shi Huang's other sons and daughters, which could be a difficult task if he was among them. This theory was more likely to be true than the other three.
Life
After Qin Er Shi's death, Zhao Gao chose Ziying to be successor, and changed the ruling title "emperor" back to "king" because the Qin Dynasty at that time was as weak as the former Qin State, which no longer ruled the whole of China, but held onto only Guanzhong. Ziying was the only person within the Qin imperial court to defend and try to persuade Qin Er Shi against the wrongful executions of Meng Tian and Meng Yi. He lured Zhao Gao, the regent who assassinated Qin Er Shi, into a trap and killed him. Ziying later surrendered to Liu Bang, the leader of the first group of rebel forces to occupy Xianyang, the Qin capital. He was eventually killed along with his male family members by another rebel leader, Xiang Yu.
