We use nouns to refer to people, places, things, events, substances or qualities.
There is no fixed rule about the nouns which are the same in masculine and feminine genders.
We just have to study these words and remember that they remain the same in the two forms.
- My favourite aunt is a doctor.
- My favourite uncle is a doctor.
- Adam likes cars. He is a good driver.
- Julia likes cars. She is a good driver.
- My dad works at school. He is a teacher.
- My mum works at school. She is a teacher.