29 August 2008

Fun with DNA

I have two children, who we can call "Sandy" and "Chris," and four grandkids, 2 boys and 2 girls.

Following my older grandson’s Y-DNA brings us to Germany, maybe around Bremen. My younger grandson’s Y-DNA goes back to Poland, near Warsaw perhaps. Two of my grandkids’ mtDNA goes to Carinthia, Austria. The other grandkids’ mtDNA reaches to Northeastern Ukraine.

Both of my children had the same father and neither had children by more than one partner. Do I have two sons, two daughters, or one of each?


pastprologue said...

I used to hate Logic puzzles! I say one of each. If you had 2 girls, the grandkids would all have the same mtDNA. On the other had, 2 boys would result in different mtDNA for each set of grandkids, but it would also give your grandsons the same Y. So, one of each is my final answer.

Randy Seaver said...

Good question...a brain teaser late on a Friday afternoon.

I think that you have one son and one daughter.

You cannot have two sons, because your two grandsons have different Y-DNA.

You cannot have two daughters because your four grandchildren would have the same mtDNA.

So you must have one son and one daughter. And each must have one son and one daughter because of the different Y-DNA and mtDNA signatures.

Right? (I hope!)

Cheers -- Randy

Roger said...

You have one of each.

Genealem said...

You have one son and one daugther.

For example: Your son has Ydna from Germany and is the father of the oldest gr-son. His wife has mtDNA from Austria and the oldest gr-son has her mtDNA. This grandson has a sister with her mom's mtDNA from Austria, as well.

Then you have a daughter who married and has a daughter whose mtDNA is from the Ukraine (Therefore you must have the same mtDNA.) The daughter has a son who has his father's Ydna from Poland and this younger grandson's mtDNA is from the Ukraine.

In summary:
Your son has a boy with Ydna from German and mtDNA from Austria and a daughter with mtDNA from Austria as his wife's DNA is from there.

Your daughter has a son who has his father's Ydna from Poland and his mother's DNA from the Ukraine. She also has a daughter with her mtDNA from the Ukraine.

(Of course in reality the combinations could be switched, but these are used for clarity.)

However, although this is a nice puzzle, DNA cannot determine these locations accurately at this time.

Sharon said...

You got it, Donna! Genealogy is full of pesky logic problems and I bet you're really good at them now.

Sharon said...

Like you said, Randy, this required logic as well as expertise. You had to know that the Y-DNA follows the male line and mtDNA is from the mother. Glad to get your brain going on a Friday afternoon.

Sharon said...

I can't give you credit for this one, Roger. You did not show your work, so I do not know how you came to the answer. I don't mean to accuse my own husband of cheating, but rules are rules.

Sharon said...

Excellent point, Genealem. I should have said, "Following the paper trail up the Y-DNA and mtDNA lines...." If DNA testing gave the results I laid out, I'd sign those kiddies up fast! No way can one get results like that from a DNA test! As it is, none of them or their parents have had their DNA tested and the paper trails for most of them are darn short. Glad you realized it was just a logic puzzle and played along. You did great.