If I have B+ blood, and so does my wife, how can our son have O+ blood?

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Biren Desai

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Biren Desai asked the Naked Scientists:

I have B+ Blood and my wife has also B+ group. But I wonder my son has O positive group, How?

What do you think?


Offline RD

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Don't file for divorce Biren...

Two parents with B blood type can produce a child with either B or O blood type.
« Last Edit: 21/06/2008 21:37:07 by RD »


Offline rosy

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Each of you will have two genes for ABO grouping. O genes don't express a protein, A and B express the A and B proteins respectively.

So if each of you has an O and a B gene, you'll both have B-type blood, but you'll each pass on only one gene (either O or B) to your baby so if both of you happen to hand on the O gene the baby will have O type blood (25 % chance), if one of you passes on an O and one a B gene the baby will have B type blood (50 % chance) or you might both pass on a B gene (25 % chance) the baby will have B type blood.


Offline thedoc

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Offline hitendra_bhatia

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Same case here that Mine & mine wife is having the same blood group B+, and our daughter is having the O+.

I understood here that this could be either B or O, I want to know that whats is approx. probability of B & O globally and also if you can tell what would be for Indian cases.

Hitendra Bhatia


Offline CliffordK

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Here is a list of the prevalence of various blood types around the world.


O+ is one of the most common blood types.  B+ a little less so.

As far as your chance of having an O+ child. 

The A, B, and Rh+ genes are essentially dominant. 

If you and your husband are B+, then you could either be:

B/B or B/O   and either Rh+/Rh+ or Rh+/Rh-

Since your child is O+, we know that both you and your husband are B/O.  We don't know which Rh genes you express.

So, if you have another child, then it could be:

BB  (both maternal and paternal B, (B phenotype))
BO  (maternal B, paternal O (still B phenotype)
OB (maternal O, paternal B (B phenotype)
OO (maternal O, paternal O)

So, each of your children has a 75% chance of being B, and a 25% chance of being O.

If either or both parents are Rh+/Rh+, then 100% of your children will be Rh+. 
If you both have Rh+/Rh-, then as above, the child has a 75% chance of being Rh+, and a 25% chance of being Rh-.

If you both have a recessive Rh- gene, and a recessive O gene, then chances of having an O- child will be 1/4 x 1/4 = 1/16 , or 6.25%.