Blood types are controlled by multiple alleles. There are actually three different alleles; A, B, and O that determine a person’s blood type. (Although there are three alleles possible, remember that each person only has two genes for every trait.)
Of the three alleles, A and B show codominance. This means that a person possessing both A and B alleles as their genotype, has AB blood because both alleles are expressed in the phenotype. The O allele however, is recessive to both the A and B allele. Therefore, a person possessing both A and O alleles will have a blood type of A. Likewise, a person with both B and O alleles will be blood type B because B is dominant, and therefore, masks the O allele.

am o- pure african kenyan.is it possible to find this blood type in africa?
If your African Kenyan..then I would say yes…..
I am O+ my parents are B+ so how ome I am O+?
A Mother and Father that are both B can have an O child. I am attaching a link to this comment as to possible blood type outcomes.
http://rhesusnegativebloodgroup.com/2012/03/09/blood-typing-facts/
* Chart data is from the Blood Bank.
hi just curious my mother o rh neg partners mother o rh neg partner abo- me o rh neg my grandmother likly o rh neg as she had several still bornes my children will be what
To know what your children will be we need to know what type your partner is…Does he know (A, B, AB, or 0)? Then I can help you.
Some one asked me: “What type of blood with my child be if I am O Rh- and my partner is AB Rh-?”
The answer is, the only outcome for your childs’ type could be: Blood Type A Rh- or B Rh-. If you are O and your partner is Ab, you will NOT have an AB or O child. This is just how the genetic variations work with those two types.