Why do some middleeastern/eurosian/Asian men expect from their wifes to stay with their parents or to look after their parents?

This is one of the reasons why marriage scares me. One of my cousins's husband made her wife to stay with his mum after his dad died. His mother ain't very old or ill. She told me that his husband was not like that before marriage and so she is shocked too.
Her mother in law does not want to stay alone but also intereferes herself in their marriage. I swear 90 years old western people are more independent than some 40-50 years old middleeastern, Asian/euroasian mother-in laws who expect from their daughter in laws to take care of them.
Why do some middleeastern/eurosian/Asian men expect from their wifes to stay with their parents or to look after their parents?
Post Opinion