How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Ken Your Own Question
Ken, Postgraduate doctor
Category: Medical
Satisfied Customers: 6558
Experience:  Working as a Doctor who Cares since 2001.
Type Your Medical Question Here...
Ken is online now
A new question is answered every 9 seconds

My blood type is A positive and my sister is AB negative.

This answer was rated:

My blood type is A positive and my sister is AB negative. Does this mean that we don't have the same biological parents.

No this does not mean that you do not have same biological parents.

If parents blood group is A and AB than child can have blood group A, B or AB. Even if both the parents are Rh positive than too it is possible. In nutshell it is possible that you do have same biological parents.

Wish you best of health. God bless
Customer: replied 6 years ago.
Hello - Sorry to trouble you again but I thought that both parents had to have at least one negative setting to have a rh negative child. - I am willing to pay an extra amount to have a more detailed answer. Thank you.
Customer: replied 6 years ago.

Hello again Dr. Ken - Sorry I should have mentioned that my fathers blood type was A positive but I do not know what my mothers blood type was.


I can understand your anxiety.

Let me explain in a bit detail.

People are divided into four major blood types: A, B, AB and O, depending on which antigens they have. Every individual inherits one antigen from each of their parents and the A and B antigens are called the 'dominant' ones. This means that if a person has one B and one O antigen the B will be dominant over the O and their blood reacts as type B. It is quite possible for children to have a different blood type from their parents, even if both parents have the same blood type. For example, if both parents are type B and have the BO antigens, they could have children who are BB (B antigen inherited from both parents), BO (B from one parent, O from the other) or OO (O antigen from both parents).

Rh status {positive or negative} works in a way similar to Blood type groups. If you are Rh positive, you may have genes for both positive and negative. If you are Rh negative, you have two genes for Rh negative.

A and A A, O B, AB
A and B A, B, AB, O no
A and AB A, B, AB O
A and O A, O B, AB
B and B B, O A, AB
B and AB A, B, AB O
B and O B, O A, AB
AB and AB A, B, AB O
AB and O A, B AB, O
O and O O A, B, AB


If your fathers blood group is Rh positive that means his child can be either positive or negative. But if both the parents have negative Rh than their child can not be positive.

I tried to make it as simple as possible!

God bless
Ken and 7 other Medical Specialists are ready to help you

If your Father is A positive that means he has dominant A gene along with o gene and both positive and negative Rh. So he can pass either A or O as well as positive and negative Rh.