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Inferred chromosome mapping
Recently I have become aware of how, by using DNA information from close relatives, such as parents, we can work out where segments of our DNA came from. This technique is called deductive mapping, inverse mapping, or inferred chromosome mapping.
The chromosome you inherited from your father is actually a combination of DNA from your paternal grandfather and paternal grandmother. In the same way, the DNA from your mother can only come from your maternal grandfather or your maternal grandmother.
So, if you find DNA on the chromosome that you inherited from your father that did not come from your paternal grandfather then it must have come from your paternal grandmother. This works in the same way to matches on your mother’s side.
Of course, after watching a video by Blaine Bettinger and reading blogs by Jonny Perl, I was desperate to have a go! I was lucky to have tested both my parents and have some interesting close matches to try it on.
My father Ken and Bev are related via my dad’s father James via two different relationships.