Riddle me this!! (Read the description)?

A father and son are driving along through the country and are involved in a horrible car wreck. 2 ambulances come and take both father and son to the same hospital. Both are wheeled into separate operating rooms. The doctor comes into the boy's operating room and looks down at the boy and says "I can't operate on this boy, he's my son".

How is this possible?

If you already know the answer to this do me a favor and let people try to figure it out first. Just for fun.

Updates
+1 y
Yes the father and the son in the wreck were father and son.
Updates
+1 y
OK it looks like most knew this. Yes, the doctor was the son's mother. This was a riddle to test how deep gender stereotypes run. Most people instinctively just ASSUME the doctor has to be a man.
Riddle me this!! (Read the description)?
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