This depends on the strength and nature of the relationship between them. I think in ethics and behavior the person must be the best teacher for his children and his wife.

Mohannad, in the area of moral I agree completely with you but when it comes to academic teaching they would prefer a different teacher. I talk from personal experience especially when they are in their adolescent stage for the children and wife if she is running higher programmes.

My kids do not prefer to listen/pay attention to an outside teacher(s) instead of me. Probably this is not a common for other people.

In practice doctors send their children and wife to other doctors and teachers to other teachers, quite common in pakistani society

Dr Mushtaq Ahmad, you are right. It is a good practice.

Rzger, may be it is because they are still kids, when they grow to adolescent age they would prefer outside teachers to teach them.