6
Aug

How Much DNA Do You Share With a Parent?

Do you want to know how much DNA, in centimorgans and percentages, you share with a parent? In this post, learn the answer, plus much more!

Everyone was born with two parents, and it is very interesting learn more about the genetic connection to these very important individuals. After all, without them we would not exist.

How Much DNA Do You Share With a Parent

Many people who have done DNA tests along with their parents find themselves wondering about the nature of their shared DNA. Is the amount they share within the normal range?

My sister and I both did tests with Ancestry and we found it interesting to learn who showed up as a closer match to mom and dad.

Since my sister looks most like my dad, we figured she might show up as a slightly closer match. She did, though I am not sure that this has anything to do with why she looks more like him than I do.

Does DNA come from mom or dad?

We inherit DNA from both of our parents. Below, find out exactly how much DNA is shared in percentages and centimorgans with mom and dad.

Plus, you’ll find out how X-DNA, mitochondrial DNA, Y-DNA, and autosomal DNA affect which parent shares more total DNA with us.

What percent of DNA do you share with a parent?

Each person shares exactly 50% of their autosomal DNA with each of their parents. This is because each person inherits 50% of each parent’s 22 numbered chromosomes.

Our autosomal DNA is contained in our chromosomes numbering from 1-22. Each of these chromosomes is a specific length and is always the same length in every human.

How is DNA shared with parents?

Each person, including each of our parents, has two copies of 22 numbered of chromosomes. The two copies of each chromosome go through a special process called “recombination” to create a brand-new copy of the chromosome to pass down to their child.

The recombination process takes parts of each of the two copies of every chromosome in order to make a new chromosome of the same length. Each of our parents’ chromosomes were inherited from their parents, our grandparents.

This is why we all have two copies of each chromosome, too. One copy of each chromosome was inherited from mom, and the other one was inherited from dad.

Since we inherit one copy of each chromosome containing our autosomal DNA from each parent, we end up sharing exactly 50% of this type of DNA with both of our parents.

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How many centimorgans do you share with a parent?

Each person shares about 3600 centimorgans with either parent. This equals 50% of the approximately 7200 centimorgans that a human has in their 22 numbered chromosomes.

Centimorgans are a handy unit of measurement used to measure genetic distance. This word is is abbreviated using “cMs” or “cM”.

If you and your parents have taken a DNA test, you might notice that on your DNA results, you share fewer than 3600 cMs with your mother or father match. This is completely normal, as the DNA testing companies don’t test every location in our genome.

In other words, even though you likely do share just about exactly 3600 cMs with each parent, your DNA results will probably show that you share between 3400-3600.

For example, I share 3,384 cMs, 3,456 cMs and 3,528 cMs with my mom, as seen below on three DNA testing sites:

Example of parent DNA match across three testing companies, shows number of shared centimorgans for two sites

More important than the exact number of centimorgans that I share with my mom is the estimated relationship that each site displays. She’s my mother – there’s no way around it!

Do you inherit more DNA from your mother or father?

As I mentioned in the previous sections, we do share exactly 50% of our autosomal DNA with our mother and father. This isn’t the only DNA that we inherit from our parents, however.

Both males and females inherit mitochondrial DNA, present in almost every cell in the body, from their mothers. In addition, a recombined X-chromsome is passed down from every mother to all of her children, both male and female.

Fathers also pass down additional DNA, in the form of their entire Y chromosome, to all of their male children. They also pass down their entire X chromosome to their female offspring.

So, who’s the winner? Do we share more total DNA with mom or dad?

Mom comes in as the clear DNA inheritance winner. Apart from 50% of her autosomal DNA, we also find that we have at least 30 trillion cells, most of them containing copies of our mother’s mitochondrial DNA within the mitochondria of our cells.

Is Mom or Dad’s DNA more dominant?

Even if we do share a little more of our overall total amount of DNA with our mothers, we might actually be a little more like our fathers. Our paternal genes tend to be slightly more dominant than maternal ones.

Conclusion

I hope that this post has helped you understand more about how much DNA you share with your mother and father, and how to understand the cMs and percentages of shared DNA.

If you have any questions about something that you read in this post, or about your shared DNA with a parent, please feel free to join us in the discussion below.

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