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smithsworldwide (Admin)
Does both a brother and sister have mom’s mtDNA?

Posted by smithsworldwide in Smith DNA on June 4, 2014 Views:(13777Replies (0)
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Got a question on exactly how mtDNA gets passed down.First, here is a photo of how this works with Smith. Note the 2 different surnames. On the left the female Smith marries a male Jones. Both Jones sons and daughters get a copy of mom’s mtdna. However, the sons do not pass down mtdna, only the daughters. On the Smith side, the male Smith is married to a female Jones. The female Jones passes down mtDNA to both Smith sons and daughters (the male Smith does not pass down mtDNA). When son Smith (right)  marries daughter Jones (left), the two resulting children get copies of mother JONES mtdna. ON the right, the 2 Smith daughters, regardless of which male they marry, will give a copy of their mtDNA to resulting children.

I also think this is a terrific site that not only explains it and has a graph but has a practical application (Missing POWs)  Go to this page and click on DNA Explained

The basic idea is that mtdna gets passed down by the female. If a mom has 2 kids, one son and one daughter, both get the mtdna, thus they both should have the same mtDNA haplogroup. However, ONLY the daughter can pass it down to her children, the son does not. Thus, if you are talking about a current generation, both the son and daughter should match mtdna haplogroup but if a generation before that (grandmother, uncle, aunt, etc), the children of the uncle (nieces, nephews)  would NOT get that mtDNA passed down.