Thursday, February 9, 2012


Tonight someone asked me if you can determine your blood type based on that of your spouse & kids, if you know all of theirs, but not your own.  If someone reading this can answer better than my attempt, please correct me or add to this post!  

I dusted off an old biology text book & looked for the section on blood type genetics.  (Campbell, Neil A. Biology. 4th Edition. Riverside, CA; The Benjamin/Cummings Publishing Company, Inc. 1996.)

Basically, there are 4 blood types: O, A, B, & AB.  Blood type is determined the absence or presence of a blood protein on your blood cell.  Which protein you do or do not have is controlled by multiple alleles of one gene.  There are 3 alleles: i (recessive), Ia (co-dominant with Ib) & Ib (co-dominant with Ia).  You get one from each parent, & the combination of the two alleles is your genotype.

Phenotype (exhibited trait) --> Genotype (genetic makeup)
Blood type O can have only one combination: ii
Blood type A can be Ia-Ia or Ia-i
Blood type B can be Ib-Ib or Ib-i
Blood type AB can only be IaIb.

Here is a punnett square/table I made that can help you see possible blood types based on parents' blood types.  To keep it simple, I did not include Rh+/- or other factors.

I think that it would be much easier to get a blood test than it would be to deduce your blood type via this table!  If you have ever given blood, the site you donated at should have your type on record.  
I hope that answers your question!

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  1. wow!  more complicated than I thought!  of course!  awesome table, you made that? not copied it?  wholly moses!  I was kind of hoping it was like eye colour, I have blue eyes, hubby has blue eyes, kids can only have blue eyes as you have to have two blue genes to have blue eyes!  hee hee!  well I eliminated two blood types, including the type I thought I was until I had one of my kids and his blood type didn't match what I thought we would have!  hospital cutbacks when I had third child they no longer tested their blood type & tell you, so don't know my youngest child's blood type either, but now I can guess!  ha ha!  thanks!

  2. I did make the table; I'm glad it helped!

  3. With blood types, if your two kids that you know the blood type of are different from your husband, than that is probably your blood type. I work in a hospital in postpartum unit. The only time they test a baby's blood type is if the mom is 0 pos or neg, or if she has a negative rh factor. So if they tested your first two, then you prob are O or have a neg rh. Your ob doctor that delivered your kids probabl has your blood type on record as wel because they have to know. Did you get rhogam shots during pregnancy? If so, then you are a negative blood type for sure.

  4. this testing happened 20 yrs ago & 18 years ago by the time I had third child they no longer routinely tested babies.  I'm pretty sure I'm not O and according to jess' chart I couldn't be.  definately not negative rh as that is very important to know if you are pregnant,  never heard of a negative factor until we were thinking of having kids and my husband told me all about it as hie is


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