Angela writes:







If I'm type TU, what type are my kids? The first thing to understand is that each of us has two blood type genes. Each parent can pass only one of his or her genes to each child; and if we have two different genes -- as in the AB type -- it can be either of those genes.



Second, when we say, "I'm type B," or "He's type AB," we are referring to what geneticists call the phenotype. It's the outward face of the genotype, the full ABO signature (always composed of two genes).



Third, the O gene is recessive to both the A and the B genes. The other way of saying this is, both the A and the B gene are dominant to the O gene. I am "type A" or "type B" whether I carry a second (recessive) O gene or a matching A or B gene.



Fourth, the A and B genes are co-dominant: when both are present, neither is recessive to the other. If both are in the genotype (full profile: A, then both are in the phenotype (blood type A. In similar fashion, if you are type O, we know you have two O genes ~ if you had only one O gene and one A or B gene, the A or B must dominate: you would be type A or type B, respectively, not type O.



This all sounds a little confusing at first, but you'll get the hang of it. Here's how it works in parentage:



Type AB can pass on either an A or a B gene to a particular child -- but not both.



Type O has only an O gene to contribute to a child.



Type A can give an A gene to a child. However, we can't tell a type A person's genotype by knowing their phenotype. The genotype could be A(a)(with only A genes to give to a child) or A(o) (having an O gene available as well).



Type B is in the same relative situation as type A. There could be a recessive O gene lurking in there (Peter calls it "grandma's revenge!") ready to match up with a mate's hidden O gene, to produce a type O individual from two type B parents!



By understanding

(1) that each person contributes one gene to offspring;

(2) that A and B are both dominant to O, and co-dominant with each other; and

(3) that knowing the "phenotype" of an AB or O person lets us know their "genotype," but knowing someone is type A or B gives us only the "public" half of that information -- the second gene is unknown;



will allow you to figure out the possible blood types of offspring if you know the two parents' blood types. With some combinations, there is only one possible result (two type O parents will always produce type O kids). With others, it's possible that Junior could be any one of the four types (a type A mom and type B dad, both with a recessive O gene... see what I mean?). In your original example, it depends on the other parent. Type O? This pairing will produce only type A (A(o)) and B (B(o)) children. Type AB? Could be type As, type Bs and/or type ABs.



The most elegant way to present this information is in graph form (a "Punnett square"), but I hope yakking my way through it has shed some light for you.



:-D

Soy for Bs: The short answer is, no ~ Bs need not absolutely exclude all soy products. Plain soybeans and small amounts of soy flour are allowed for B secretors. Soy milk is neutral for B nonsecretors. However, it's not an ideal food for your type, any more than rye bread is for mine. Since so many soy products are designed to mimic or replace either dairy foods or meats, you'll get far better value for your money (and flavor, for that matter) by choosing the originals.

Angela in Nova Scotia submitted three questions ~ this is the first:



The Fish/Mercury Conundrum: We’ve all heard about the benefits of including fish in our diets. The American Heart Association now recommends two-to-three servings of fish per week. Why? Lean protein, for starters. The big deal, however, is the omega-3 fatty acids abundant in fish, which aid healthy brain and vascular development in babies and confer protection against heart attacks and strokes in adults. They have also shown potent healing properties in connective tissue disorders and cholesterolemia. Omega-3s are not blood-thinners; they are blood de-sticky-fiers. Brand new word, what do you think of it? :-D In other words, type Os need not worry that their natural propensity toward more copious bleeding would be magnified by eating more fish. It is the tendency of platelets to clump or clot, rather than blood plasma-to-cell ratio, which is affected by these EFAs.

Fatty, cold-water fish like salmon, sardines, mackerel and lake trout are the recommended species due to their relatively low tested mercury levels. The FDA’s cutoff point is 1 part per million, 1/10th the levels found in mercury-related disease. Tuna is considered a fence-sitter: the average reading is around .2 ppm methyl mercury. Interested parties disagree as to whether this fairly low level should place tuna in the OK category or the red-flag zone, since it (canned tuna particularly) is such a popular and frequently eaten food in the U.S. The big predators like shark and swordfish can accumulate higher levels, sometimes reaching 1 ppm, and conservative health professionals warn against eating them more than once per month.

Pregnant women in particular should choose wild fish, both freshwater and small saltwater dwellers, over the big oceangoing migrators, because the developing fetus is extremely vulnerable to nervous-system damage from mercury in the diet, air and water – and the older and larger the fish, the higher the mercury can climb. Farmed fish are usually raised under conditions you don’t want to know about, and with feed you wouldn’t even want in your compost. Try your darnedest to get wild catches, and research the environment of your freshwater choices: they pose a concern only if caught near areas of industrial pollution.

The fish recommendations in Peter's books are made with clean, low-mercury specimens in mind. They are based on biochemical properties, rather than potential environmental poisoning. So the best approach is to evaluate your seafood sources. Fish from the eastern seaboard and major rivers of the United States and parts of Central and South America are more likely to push the mercury levels than are those caught off the coasts of less industrialized areas of Canada and Alaska. :-)