Happy Grandparents Day (with some interesting DNA facts thrown in)!

Each of us has two grandmothers and two grandfathers, genetically speaking.  

I'm a lucky lady to have two ready-to-greet me and serve me chicken and noodles and ruffle my hair whenever I head back to Indiana for a visit. Happy Grandparents Day to them today! 

My Grandma Mary and Grandpa Leland, now great-grandparents to an energetic brood of 17 kids, have been married since 1948. No one on Earth can make chicken and noodles like my grandma, and no one can solve a mechanical engineering challenge better than my "Mr. Fix-It" grandpa.  

They have passed down more to me than just DNA; they have also passed down their years of wisdom. 

My grandmother's marital advice at the time of my wedding was short and sweet: "Hang in there!"

That seems like sage advice but seems to have worked out pretty well for her so far! Wisdom imparted to me by my grandpa included learning how a toilet flapper works and how to change the brake pads on a car. 

The genetics textbooks I read many moons ago told me I should have gotten 25% of my DNA from Grandma Mary and from each of my other three grandparents as well. At the next generation up, that means I should have received 12.5% DNA from each of the eight people I know as my great-grandparents. For each "great" you add, the amount of inherited DNA from a grandparent is cut in half.

Modern advances in genetics (and multiple generations of families deciding to undergo consumer DNA testing) have allowed us further insight than biology textbooks alone. Some astute collectors of data in the genetic genealogy community have collated and compared information about the shared amounts of DNA between people with known relationships. These studies have allowed us to see just how close the textbook facts match reality.

Studies of shared DNA amounts between family have revealed surprises, one being that the amount of DNA we inherit from our grandparents falls into a wide range, instead of fitting tightly at 25%. 

Charts like that produced by the DNA Detectives and from Blaine Bettinger's Shared cM Project show us the range of DNA we share with a second-degree relative (a group that includes grandparents) may be more like 18-32%.

Second-degree relatives are a group that includes grandparents as well as grandchildren, half-sibs, aunts, uncles, nieces, and nephews.

We can give Mother Nature and the randomness of DNA inheritance thanks for that!   

If this topic interests you and you would like to read more, this fantastic post on The DNA Geek blog goes further into detail about the shared DNA between family members. 

Did you inherit more than just DNA from your grandparent? Did you have a grandparent who you may not have shared DNA with but who meant the world to you?

Leave a comment or story below about your loved one to celebrate Grandparents Day with me today!

- Brianne