A simple blood test can reveal a lot about a person. It also can tell you important information about who that person is related to. When blood test results reveal unexpected things, this can lead to family problems, (including divorce). Genealogists may want to keep this in mind before ordering a home DNA kit.
A student in Taiwan was studying blood types and hereditary properties in his junior-high school biology class. He learned that his blood type was B, and that his father’s blood type was A. This lead the student to ask his father how that could be possible. It did not match what he learned in class about how blood type is passed from parents to children.
Your blood type was passed down to you from your parents. Each parent gives you one gene for blood type, (for a total of two). You could, potentially, receive a gene for type A, type B, or type O. The combination of those genes is what determines your blood type.
The father had type A blood. It is possible each of his parents gave him the gene for blood type A. Or, one of his parents could have given him the gene for blood type A, and the other parent could have given him the gene for blood type O. His wife, the boy’s mother, also had blood type A.
Now, the son has blood type B. There are only two ways to get blood type B. Either both of his parents gave him the gene for type B, or one parent gave him the gene for blood type B and the other parent gave him the gene for blood type O. The problem is that it would be impossible for either of his parents to give him the gene for type B blood. So, where did that come from?
The man and his wife had been married for twenty years. Two years after they were married, the wife gave birth to a baby girl. Eight years after that, she gave birth to a son. The son was born with achondroplasia. This is a genetic condition that causes a person to have extremely short stature. Worldwide, achondroplasia happens in around 1 in 25,000 births.
The man ended up taking both his son and his daughter to get a DNA test. Sadly, it turned out that neither one of them were actually the man’s biological children. Imagine how traumatic it would be to make this kind of discovery! In this case, it led to a divorce, where the children’s mother revealed that she began an affair less than two years after getting married. Both of her children were the biological offspring of the man she had the affair with.
Image by Sean Micheal Ragan on Flickr