Added: A lot more information has come our way since making this post. This information can be found at our forum.
Recently I have met a lady who is 0 negative and her husband is AB positive.
They have two children:
One 0 negative like the mother and the other AB positive like the father.
According to the blood type calculator this is impossible:
This is yet another example of how little blood type studies are being taken seriously when the number 1 blood type calculator published by the University of Arizona generalizes their calculations to the degree where their tool becomes unreliable.
In case this causes you to question the paternity, you can try the calculator to match any type of combination of an 0 negative parent and an AB positive child and you will get the same results:
Do you know someone who is 0 negative with an AB positive partner?
Feel free to leave a comment if you have real life experience with this subject matter.
~ Mike Dammann