# What determines your blood type? My mother's blood is AB - and my father's blood was O +, I have A +, is that possible? Both my kids are A+ and their father is O -. Is that possible?

Aug 3, 2017

Your blood type is determined by genes inherited from each parent which combine to give you your specific blood type. Both your blood type and those of your children are possible genetically.

#### Explanation:

The genotype (genetic composition) of blood groups is slightly different from the phenotype (manifestation or expression).
To explain:

1. A Blood Type can be genetically A-A or A-O.
2. B Blood Type can be genetically B-B or B-O.
3. AB Blood Type is always genetically A-B.
4. O Blood Type is always genetically O-O.
5. Rh+ Blood Sub-type can be genetically D-D or D-d.
6. Rh- Blood Sub-type is always genetically d-d.

Since one gene each comes from either parent for the Blood type and one gene each for the Blood sub-type, it is possible for the child to have a different Blood type from the parent, but only with a combination of the existing genes.

Your mother is AB- (genotype A-B and d-d), and your father was O+ (genotype O-O and D-D or D-d).

So you would have inherited an A and a d from your mother, and an O and a D from your father, making you genotype A-O and D-d. If you see above, that would make you phenotypically A+.

[The other possible combinations from your parents would be A-, B+, B-, if your father was D-d, or just B+ if he was D-D]

In the case of your children:
You are A+ (genotype A-O and D-d as seen), and your children's father is O- (genotype O-O and d-d).

So your children would have inherited an A and a D from you, and an O and a d from their father, making them genotype A-O and D-d. If you see above, that would make them phenotypically A+.

[The other possible combinations from you and your children's father would be A-, O+, and O-]