How can a baby have a totally different blood type than either of its parents?

When the sperm meets the egg in the womb, it is only carrying 1/2 of the genetic code that the fetus will need. The other half is supplied by the egg. We have 23 sets of chromosomes (convienently numbered 1-23) mom donates 1/2 of the 23 pairs and dad donates the other 1/2 of the pairs. They mathc up together and then start dictating how our bodies are to be built, what color of hair we have, what our eyes will look like, how tall we will eventually become and what type of blood we will have.

Blood type is co-dominant (with the exception of type O). Meaning you get one type from mom and one type from dad and they express equally.

There are 3 kinds: A, B, O

A combination of AA (Where you get one A from each parent) results in type A blood.

A combination of AB (Where you get an A from one parent and a B from the other parent) results in type AB blood.

A combination of AO (Where you get an A from one parent and an O from the other)results in type A blood.

A combination of BB (Where you get a B from each parent) results in type B blood

A combination of BO (Where you get a B from one parent and an O from the other) results in type B blood.

In order to get tyoe O blood, you must get an O from each parent.

A simple blood test cannot tell you whether you are BO or BB if you have B blood, for example, but a genetic test can tell you if you are both really the parents.

Having a child with a different blood type than either of the parents isn't that uncommon and definetly possible. Let's take a couple, for example, and one of them is AO (type A blood) and the other is BO (type B blood). The child could easily recieve an O from both parents and be type O, different from the parents. The child could also recieve A from the AO parent and a B from the BO parent and then the child would have AB blood.

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Ok here are the genetics of blood type, I am not gonna go into negative or positive though. There are blood types A, B, AB, and O. All the types are dominant except O which is recessive. Blood type A will have two genes and it has to be either (A, A) or (A, o) again because O is recessive. Blood type B is the same as A so it would be (B, B) or (B, o). In order to be blood type AB you can only be (A, B), and O can only be (o,o). So let's say one parent is (A, B) and one parent is (o,o), the child would be (A, o) or (B, o) giving it blood type of A or B which neither of its parents are. I hope that makes sense.

They can't. It's always either one parent's blood or the other's or a combination of both so a baby with two parents with blood type 0 will never nave blood type AB. If it does, I will immediately try to find the real father. :-)

Yes, it's possible. For example, one parent can be Type AO (often shortened as Type A) and contribute either the A or O allele while the other parent can be Type BO (often shortened as Type B) and contribute either B or O, so the baby could either be Type AO, BO, OO or AB.

http://www.drgreene.com/21_59.html

Can it??