If DNA testing was being done on samples obtained from the bones from two parents who were siblings, a saved blood sample from their long-dead daughter, and a sample obtained from a recently deceased man, for the purpose of establishing a familial link between the recently deceased man (Who is, in fact, the brother of the long dead daughter) and the three others, would the testers be able to tell that the parents were siblings that had had incestual relations, as well as the parents of the other two? I’m a mystery writer, looking for a little help! Thanks to any who take the time to help 😀
Hmm. Well siblings are, theoretically, 50% related. Therefore any children had by them would be 25% related to their siblings and 50% to each parent.
The children would show lower heterozygosity than normal if their parents were related. I suppose if you could show the two dead people were siblings and had higher than normal homozygosity, then yes you could figure out that their parents were siblings.