Who Is Lying? Me Or Him?

Riddle: There are four doctors who say they have a brother, but the brother says he has no brothers. Who is lying?

Answer: Neither, the doctors are his sisters!

Source: https://www.riddles.com/3854

There are four doctors who say they have a brother, but the brother says he has no brothers. Who is lying? — Who Is Lying? Me Or Him? by DREAMON v1.

Riddle: There are four doctors who say they have a brother, but the brother says he has no brothers. Who is lying? Answer: Neither, the doctors are his sisters! — by DREAMON v2.