Another blood type question caught my eye and I started wondering…my ex boyfriend had O+ blood type. His mother told me that he was tested as a child and again as an adult. About 2 years ago, he was asked to donate blood (his father is a surgeon). When he went to donate, they tested his blood type there in front of all of us and he was O-. Because of the original test, his father asked that it be tested again. Again it was O-.
I have actually heard anectdotal evidence of this happening, but I was wondering what either the science was behind it, or whether the original tests were just bogus and that it is an absolute impossibility.