Which Grandparent Are You Most Related To?
About Autosomal DNA
Autosomal DNA is like the backbone of your genetic code. You get it from your mom and your dad.
So where did they get it? From their parents - your beloved grandparents! Your parents pass down a mishmash of whatever autosomal DNA they inherited.
Here's how it works. Say your dad got 50% of his DNA from his mom and 50% from his dad. The DNA he then gives you is a random combo of both. Maybe 60% came from Grandma and 40% from Grandpa.
It's kind of like shuffling two decks of cards together and dealing yourself a hand. You end up with a mix of both decks.
This explains why you share different amounts of autosomal DNA with each grandparent. You essentially got a different "hand of cards" from each one.
On average, you'll share around 25% of your autosomal DNA with any single grandparent. But it ranges from as low as 18% to as high as 33%.
You've got a unique genetic mix from your family tree!
X Marks the Spot for More Grandparent Genes
Now let's talk about X-DNA. I promise it's not nearly as confusing as it sounds.
Ladies have two X chromosomes. A man have one X and one Y chromosome.
If you're a girl, you got one X from your mom and one X from your dad. But your dad's X came from his mom. So, you have an X from your maternal grandma and an X from your paternal grandma.
That means, as a female, you share more DNA with your grandmas. You got X-chromosomes from both of them, but only one of your grandpas.
If you're a guy, you got an X-chromosome from your mom and a Y-chromosome from your dad. So your X-DNA only connects you to your maternal grandparents.
The point is, X-DNA links you more closely to your grandmas if you're female.
Other Genetic Factors At Play
So far we've talked autosomal and X DNA. But your family tree genetics don't stop there.
Other things can cause you to share more or less DNA with each grandparent:
- Recombination: The chromosomes you inherit mix together parts of your grandparents' chromosomes. Some of this shuffling gives you longer segments from one grandparent.
- Mutation: New mutations in a grandparent could pass down just to you. If your granny had a new mutation, only you two would share that novelty.
- Random chance: There's a luck factor too. Which chromosomes you inherit is random. You might simply get more DNA from one grandparent based on luck of the draw.
What Now?
Want to learn about your personal genetic connections? You can take an autosomal DNA test! These tests analyze bits of your autosomal DNA.
The results will show which segments you inherited from each grandparent based on matches with other relatives.
You'll see exactly how much DNA you share with Granny and Pop Pop! See who you got dealt more genetic cards from.
The test can also show rare mutations only you and a grandparent share. You can learn about unique health risks or physical traits passed down just to you.
Which Grandparent Should Be Tested?
So as we saw above, if you are testing a female "Granddaughter", it is usually better to use the grandmother's DNA over the grandfather's.
This is simply because the X-chromosome is passed from your grandmother to her daughter "Your Mom". Likewise your grandmother has also passed her X-chromosome to her son "Your Dad". Therefore the grandmother's X-chromosome is the more prominent chromosome found in both your mother and father.
If you are testing a male "Grandson", it may be better to test with the grandfather, as he has passed the Y-STR DNA to you father, and thus you can either perform the traditional grandparent DNA test or a Y-STR male lineage test.
Furthermore, when doing a grandparent DNA test, It is always best to test with both the grandmother and grandfather if possible, as together they represent the sum total of the DNA inherited by you father.
Knowing where you get your chromosomes from can be extremely helpful when trying to choose which grandparent is best for you to test with. And if you're not certain, speak with a DNA testing specialist, and they can help you figure things out.
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