What the book says is calculated according to the time of pregnancy in October:
Then he leaned down to look at Duan Yu's head and neck and saw a thin gold chain hanging around his neck. When he pulled out the gold chain, he saw a small rectangular gold plate engraved with the words "longevity" at the end of the chain. He turned it over and saw a small line engraved on it: "Baoding, Dali, born in 20021October 23rd+165438." .
When Duan Yanqing saw the words "Baoding for two years", his heart was sharp: "Baoding for two years? In February this year, I was besieged and seriously injured and came outside Tianlong Temple. Oh, his. His birthday is on 1 1 month, only1month apart. Is that him? He ... He is my son, when he was pregnant in October? "
Here comes the problem. Dao Baifeng and Duan Yanqing figured out the approximate date of pregnancy according to these birth dates, thus knowing that Duan Yu is Duan Yanqing's son. Duan Yu's birthday must be known where the whip festival is, so why does he still regard Duan Yu as his own son? A short whip with a ring at one end that can be held.
There is only one explanation. During pregnancy, Dao Baifeng and Duan also had a married life, so Duan won't have any doubts. In other words, Dao Baifeng didn't really know whose child Duan Yu was. Then, if Duan Yu finally marries Mu, Zhong and Wang, half of them may be really messed up!