what is the grammatical error in this sentence?

Question

Those of us who have a family history of heart disease should make yearly appointments with their doctors. and why

Answer 1

Those of us who have a family history of heart disease should make yearly appointments with their doctors.

 

  "Those" is the subject and "their" would agree with the subject.  That is not the problem.  

 

We are talking plural with "those," therefore, "have a family history" should be "have family histories."

Answer 2

YUNUS, "us" and "their" do not go together. "Their" should br replaced with "our".

Answer 3

... with OUR doctors.

 

"their" does not agree with "us."