My brother is Bo, his wife A_, and their son is A_...would not Aa or Ao x Bo produce either AB or O? What must the silent type of the mother be in the case of Bo x A_ to produce an A_? Could the baby be Ab or Ao...is there such a thing as Ab or is it always AB..or what? Thanks, John -- in Calgary, Canada

Hi, John! I assume you know your brother is B(o) because (1) he tested as type B, and (2) one of your parents was type B or AB, and the other type O.

I think your question stems from the idea of A and B both being dominant to O. This is true in a single individual, but a parent can donate either of her genes to any child.

Therefore, your brother can donate an O gene (his recessive one) to the child, and his wife can donate an A gene (her dominant one). There you are: a type A kid.

Your brother and his wife may be the classic ABO wildcard combination: B(o) + A(o). Couples with this ABO configuration can have type A(o), B(o), O or AB children. OR, they might be B(o) + A(a), in which case their offspring can only be type A(o) or type AB. In either case, a type A child is certainly possible in this pairing no matter what the silent type, or genotype, of the type A mother.

"AB" is the standard name for that blood type, but if it were "BA" instead, it would make no difference. The two letters are both capitalized because the A and B genes are co-dominant; neither is recessive to the other.

Hope this clears it up!

Born on a small dairy farm, my first role models were Errol Flynn, Leslie Howard, Kwai Chang Caine, and Dad. To be alive in this world is to be enmeshed in ambiguity -- but while my early acceptance of that state made complex things easy, it also made simple things a struggle.

Little has changed since then, except that as a result of conversations with a man who knew Errol Flynn, I struck his model from the list. Early choices can be difficult to undo. All those years spent learning to fence and studying the fine points of protocol of a variety of then-antiquated societies! Well, how was I to know? This, combined with my reading material (Shakespeare, Milton, Homer, comparative religion and ceremonial magic) made for a very odd little farm girl. As I said, little has changed since then.

My distinctly non-scientific career has included stints as librarian, dreamworker, animal rights activist, free-lance theatrical editor, medical transcriptionist, commodities trader, phone sex receptionist, dog breeder, philology student, real estate developer, legal secretary, business software consultant, florist, not in that order, and a few things I've forgotten -- the entire mishmash a result of lifelong ambiguity toward an operatic career. It is certainly true that in life we end up doing the thing we are second-best at... not yet having ended up, I'm not sure what that might be. In regard to what I'm best at, however, the aphorism holds true.

The interesting part of the story is that in 1997, my traditional Chinese medicine practitioner suggested I read the blood-type diet book written by Peter J. D'Adamo, ND. This provocative discovery lit up my world. Ambiguity miraculously disappeared from those two essential simple things: food and exercise. My enormous gratitude for this gift of freedom expressed itself in a desire to foster education about the diets and encourage others to use and disseminate the theories. So began five years of daily involvement with Peter's website bulletin board.

The rest you know. (Pretty much.) If not... check the archives! ;-)