The original riddle is of course:
"A father and his son are in a car accident [...] When the boy is in hospital, the surgeon says: This is my child, I cannot operate on him".
In the original riddle the answer is that the surgeon is female and the boy's mother. The riddle was supposed to point out gender stereotypes.
So, as usual, ChatGPT fails to answer the modified riddle and gives the plagiarized stock answer and explanation to the original one. No intelligence here.