Can parents both with positive blood types produce a child with a negative blood type

It never ceases to amaze me how many people offer opinions on blood type when they have no idea what they're talking about, even when they know it may directly affect a family.

What worries me a bit about this question is the 'for example' bit. There r much bigger problems with a child having AB blood if *either* of their parents has O blood than for the +/– thing.

Melissa is exactly right about that. Everyone has two alleles (versions of the gene) for their rhesus blood factor. Positive is dominant to negative, so whilst + & + alleles gives u a positive blood type & – & – gives u a negative blood type, + & – shows up as positive. A child takes 1 allele from each parent, so if both parents r + & –, they will have + blood types, but there is a chance each will give their '–' to the child, giving the child – & – which allows the child to be negative. For two positive parents, the chance of having a negative child is comparable to having a left-hander - not extraordinary.

Assuming the AB & O parents thing was not just an example, that is more of a problem because again u have two alleles per person, of which there r three types: A, B & O. A & B r co-dominant with each other, & both dominant to O. So AB type blood means A & B alleles & O type means O & O, but A type might mean A & A or A & O, likewise for B type. A person with AB type needs to have inherited an 'A' from one parent & a 'B' from the other. An O type parent could provide neither.

The only 2 exceptions to that (neither common) that I've heard of would be, firstly, the twin blood type thing Rebellynn mentions. (Sometimes twins r conceived, then one of then dies & is ejected at a very early stage, without anyone knowing. So a child could be born with their blood influenced by a twin no one knew of.) Secondly, the father might have a rare blood type such as Bombay blood, which prevents A & B alleles influencing blood type, leading to a blood type which would show up as O type blood even if the father was genetically A, B or AB. See http://en.wikipedia.org/wiki/Bombay_blood.

Hope that helps. If u have any more Qs about blood type, it is safer to ask them in Medicine, or possibly Biology.

My parents are both + (not sure of the exact type so I am leaving that blank lol) and I am AB-

All the + or - means is the Rh antigen is present or not. The alleles on both of the parents are +- and +- which, in the scientific world, means that both + and - types can be produced.

Hope that helped.

Yes it is possible and a complaint should be made about the person who gave such false information to the child.

Yes, I have negative blood and both my parents are positive. My sister and brother are both positive also. And yes I do belong to my Dad because I look alot like his side of the family. I have one cousin that is negative also.

no its not possible get a paternity tst

Hmm...is paternity an issue? No, I do not want to know but answer this yourself. If there is no one else then u might be the recipients of mixed up labs, have them retest. The only other thing I know if is a rare genetic thing called Chimera: In medicine, a person composed of two genetically distinct types of cells. Human chimeras were first discovered with the advent of blood typing when it was found that some people had more than one blood type. Most of them proved to be ''blood chimeras'' -- non-identical twins who shared a blood supply in the uterus. Those who were not twins r thought to have blood cells from a twin that died early in gestation. Twin embryos often share a blood supply in the placenta, allowing blood stem cells to pass from one & settle in the bone marrow of the other. About 8% of non-identical twin pairs r chimeras. Good luck.

Two negatives can make a positive, but I do not think the other way around.time to test!!

paternity test