Two A's can have an O child... Ao and Ao can both give o genes to produce an O offspring.  Same with two B's.  Or an Ao and Bo parent.  AB has only A or B to give, so can not give an o on their side to give oo in the offspring.  

Just like two brown eyed parents can be Bb and Bb to give bb, or blue eyes, but a brown eyed person with BB cannot give a b.  So the child will have brown eyes despite the color of the other person.

Quoted Text

Just like two brown eyed parents can be Bb and Bb to give bb, or blue eyes, but a brown eyed person with BB cannot give a b.  So the child will have brown eyes despite the color of the other person.

Eye color is far more complicated than that! there are at minimum 6 genes that have been identified in direct connection with eye/skin color, there are, like I said before, over 800 alleles that those genes can have, so do the math, how many possibilities are there? Example, parent 1 : BbAAccDdeeFf Parent 2: BBaaCcddEEff, keep changing it up and see what you get! (How do I know this? My brother is a University Professor of molecular biology and he helped me write a paper on it for my Honors class , requiring 8 other sources besides him  ) I think it is fascinating.

Quoted from grey rabbit

If you are an O you cannot have an AB parent! Eye color is far more complex than blood type BTW, there are only three alleles for blood type and so far there have been 800+ alleles identified that have an influence on eye color! Therefore it is possible for a blue-eyed parent and a brown-eyed parent to have a blue-eyed child even though brown is dominant.

My father had brown eyes, red hair and pale skin, my mother has black hair, blue eyes and pale skin and myself and two of my siblings have blue eyes and fair skin.  My other brother has dark  brunette hair, dark skin and dark brown eyes.  His coloring is the predominant coloring of both of my parents' siblings.  My father did have a sister who was a red head, but the rest of his siblings were dark.  My mother's siblings were all dark.  None of us got my father's red hair or my mother's coal black hair.

Weird!

I'm the only one in my family with brown eyes, my mom's are greenish, dad's blue or grey and my older bro's are pale blue. I don't know where my eye color comes from, I just know they're greenish brown (once I tried on one brown contact lense, and my other eye looked green in comparison!!   ) Also my skin's quite dark for a Finn (tho not at all so here in Spain   )

Quoted from grey rabbit

Eye color is far more complicated than that! there are at minimum 6 genes that have been identified in direct connection with eye/skin color, there are, like I said before, over 800 alleles that those genes can have, so do the math, how many possibilities are there? Example, parent 1 : BbAAccDdeeFf Parent 2: BBaaCcddEEff, keep changing it up and see what you get! (How do I know this? My brother is a University Professor of molecular biology and he helped me write a paper on it for my Honors class , requiring 8 other sources besides him  ) I think it is fascinating.

Good thing God is in charge of our genes and not me!!!!!!!

Quoted from Pixu

I'm the only one in my family with brown eyes, my mom's are greenish, dad's blue or grey and my older bro's are pale blue. I don't know where my eye color comes from, I just know they're greenish brown (once I tried on one brown contact lense, and my other eye looked green in comparison!!   ) Also my skin's quite dark for a Finn (tho not at all so here in Spain   )

Don't green eyed people carry the gene for both blue and brown eyes?

So there is no such thing as an Oa subtype?  Os can only be Os no matter of the parents blood type?

Quoted from Maus

So there is no such thing as an Oa subtype?  Os can only be Os no matter of the parents blood type?

If you are referring to strictly ABO typing, you are correct.  The A would be dominant to the o, so you would be Type A with a recessive o, or Ao.

If you are referring to the typing in James D'Adamo's book, referenced in another recent thread, I can't answer your question fully as I haven't read his book and don't know what scientific backing he uses to substantiate his theories.

I did not know there is a difference.  I thought subgroup is subgroup.  Confused now  

Quoted from Maus

I did not know there is a difference.  I thought subgroup is subgroup.  

James D'Adamo use the term blood subgroup differently than nearly anyone else.

This site is not associated with James D'Adamo so we do not use his unconventional definition.

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On this site, we are concerned with the work of Peter D'Adamo.

His diet books are concerned with only two blood subgroups. Since these subgroups are only found in type A, and you are type O, you can ignore blood subgroups.

The diet rating systems of peter D'Adamo use A₁ and A₂.

A few food recommendations differ for A₂.

Eighty percent of type As are A₁.

A1 differs from A2 because of genetic difference in the coding of the A antigen.

A single nucleotide substitution that creates a single amino acid change (proline # 156 is changed to a leucine) and a deletion mutation which causes a frame-shift which extends the reading frame.

You can test the genetics or you can use blood serotyping to identify the antigen a person has.

There are other blood subgroups but they do not play a role in determining the diet recommendations in Peter's books.  (Actually in most of his books the A subgroups are not used, only blood types are used)

a serotyping panel would help narrow down your subtype GR

Can this be "stickied" by any chance please? It is fascinating