how can bllod type rule out a possible father??

Answer 1

It's kind of hard to explain....
type O mother...type O father....type O baby
type A mother...type B father.. baby can have either type A, B, or AB
Type A mother...type O father...either type A or O
type B mother...type O father...either type B or O

Answer 2

Blood types can rule out the possible father because the blood type is genetic. This means that if the father and the baby don't have the same type of blood at all, the father is more likely to not be the father. To be more certain, take a DNA test because this is the most accurate paternity test.

Answer 3

Because blood types are inherited.

Basically its this, there are 4 possible blood types A, B, AB and O. Every person gets 2 genes, one from each parent, that determine blood type. Some genes are dominante, so they are the ones that show up when they are there, others are recessive and the dominate ones hide them.

A and B are both dominante, O is recessive.

So lets say the baby gets A from Mom and B from Dad. Baby will be AB.

If they get O from Mom and A from Dad, baby will be A.

If they get O from Mom and O from Dad, then and only then will they be O.

So if you are A, and potential daddy is O, but baby is AB, daddy isn't daddy.

But it can't be trusted. With the combinations of my husband and I, we could have a baby of any type. I'm Ao and he's Bo. We have one kid who is A which means he got A from me and O from dad,another is AB, which means he got A from me and B from Dad, but since we both have potential O to give, we could both give an O and have an O baby. Or he could give a B, I could give an O and we have a B.

Answer 4

Blood types can only provide a possibility of fatherhood, not a definitive answer.

Here's a chart which shows possible combinations, and rules out certain ones:

http://www.dnatestingcentre.com/blood_type.htm

Answer 5

Two B+ can't make an A-