Silly curiosity question

[Steve Demuth]

Makes me wonder about my family tree, the part where my Mom's sister married my dad's brother. When checking the DNA of me, my 4 siblings and my 4 cousins, would they be able to tell if there was 2, 3 or 4 parents? I'm assuming yes but no clue

It's a really interesting question. With a deep analysis of the DNA, for sure. Probably with a fairly casual analysis. Unless the two female siblings or the two male siblings were identical twins, they had quite different DNA mixes. A little example illustrates (not saying any of this is true - just making a point): If the parents of the girls were both brown eyed, but heterozygous, then one girl could easily have had blue eyes (homozygous recessive) and the other brown (and been homozygous dominant). The second could not be the parent of a blue eyed grandchild. Given the thousands of SNPs that could be tested in routine genetic analysis, you're pretty much guaranteed to find ones that identify the parents definitively.

[Steve Demuth]

That is a great story. Thanks for a smile to close the day.

Just to be clear though, the children would not have identical DNA, they would each have a unique combination of DNA drawn partially from their mother, and partially from their father. You wouldn't be able to distinguish of the two couples they got that DNA from, and they would have the same consanguinity as siblings, but they wouldn't have the same DNA any more than I have the same DNA as my non-identical brothers and sisters.

I just wanted to clarify my comment above. You wouldn't be able to distinguish which twin was a child's parent through casual genetic analysis. A thorough analysis would almost certainly reveal the answer though. Even though identical twins start with identical DNA, by the time you get to the point that they are producing gametes, the cell line has undergone many divisions, and accumulated some mutations. Looking carefully at a full genome, would reveal the truth. This is in fact how the strain analysis you hear about for the SARS-CoV2 virus is done - nominally, all SARS-CoV2 virus should be identical, but their mutations get in and get propagated, allowing one to identify and track strains. It happens of course much more frequently in a virus, and their are many more viral replications, but the rate in humans is high enough that you'd almost certainly be able to trace back to the actual parent.

[Jim Koepke]

Famous or rich families back in the 1700’s and before might have records and common folk want to be related to them so they take those suggestions online without one iota of proof.
We can’t trace the King name past Katherine King b1778 but the Ancestry site will take it back to all sorts of people based on hunches.

It makes it more interesting for people to talk about. The Ancestry site saying one's lineage is traced back to the Magna Carta better than saying they think a family line can be traced back to some guy who got off a boat in New York during the 1840s from somewhere in Europe.

jtk

[Bill Dufour]

I looked it up and roughly 10% of the general population are left handed. roughly 20% of identical twins are left handed. Pretty much any identical twin who is left handed has a right handed twin.
Bill D

[Jim Matthews]

I remember Alain Vigneault, former coach of the Vancouver Canucks admitted even after coaching the Sedin twins for several years he couldn't tell them apart.

He just held out their jerseys at the top of the stairs - and da boyz sorted it out.

https://theprovince.com/sports/hocke...ks-of-all-time

[Bob Turkovich]

There are two subjects in this thread that I have personal experience with - 1.) parental DNA chain 2.) identical twins

My brother and I are married to two sisters. He is two years older than me - our wives are two years apart (although reversed).

(Side note: We both have identical BS Aero E degrees from the same university. Our Masters degrees are also from the same university but in different fields. We both retired from the same company. We lived 4 miles apart - belonged to the same swim club and tennis club. We each have a son and a daughter. His are two years older than mine. The list goes on - my late mother would go through the whole list when talking to friends and would finish it with "They still don't get along with each other...")

Our sons do not look at all alike. They do, however, have similar interests and consider each other "best friends".

Our daughters also do not look alike. Their relationship would be best described as cordial.


My son and daughter-in-law have blessed us with three grandsons. The eldest is 8 years old, the other two are 5 1/2 year old twins. DNA testing has confirmed that the twins are identical.

I am a "converted" lefty; my daughter and daughter-in law are left-handed as well. All other parents/grandparents are right-handed.

All three boys are right-handed. The twins part their hair on the same side. (Sorry, Dave - no fingerprint data on the twins.)


2020 First day of school.JPG


And no, I can't tell the twins apart. The longer hair makes it even more difficult.

[Kev Williams]

2020 First day of school.JPG


And no, I can't tell the twins apart. The longer hair makes it even more difficult.

<<--Left twin's right eyebrow seems to have more of a sharp (^) arc to it, while
-->> Right twin's right eyebrow seems to have more of smooth (͡ ) arc...

-but that could just be due to how they're smiling