There’s nothing more fun as a suspense author then to have a twist in your novel. Some medical twists can be intriguing and one that is in such a category is looking simply at blood type. Knowing a child’s blood type can give you an idea if their parents are really their parents.
Let’s say a child has AB blood type, but his parents are both blood type O. I can tell you right now that those parents are not that child’s parents. How? Because you inherit a letter from each of your parents. So this child can be A, B, or AB blood type, but never O.
A parent that is just A or B blood type have an O they can pass on. It might be easier to view them as AO blood type. So if both parents were blood type A— their children could actually just be blood type O from inheriting that “O” from each of their parents. What blood type could they never be?
Here is a chart that looks at how blood types are determined. Scroll to the bottom of the page.
As a writer, have you ever used blood type to reveal that a child is not living with his biological parents when he thought he was?