When Annie, the daughter is in the hospital giving birth to her baby, she says something like " Dr. Brooks broke HER arm so HE had to fly to Maine." Apparently Dr. Brooks is a she-he!
You need to listen a little more closely....she says and I quote "Dr. Brooks' kid broke HER arm at camp. So HE had to fly to Maine this morning." So Dr. Brooks is not a he/she...his daughter is a she and that would make him a he.
Actually they say that Dr. Brooks' DAUGHTER broke HER arm at camp so HE had to fly to Maine to get HER. Don't worry, all genders are correct in the movie.