How does an Ancestry Test actually work?

Even just a decade or two ago, widely available and cheap DNA Testing was considered in the realm of science fiction. But now, thanks to an explosion in both ancestral curiosity and DNA Testing Companies, you can have a convenient in-home testing kit sent to your uncle for their birthday. Unlocking the lost secrets of your parentage, ancestors or medical conditions is now the price of a family dinner at an upscale restaurant.

But what actually happens when your cheek sample is sent off in that envelope? How do companies use your saliva to determine the nationality of your great-great-grandfather? Let’s unpack the science behind the magic.

The Science of Pattern and Elimination

Inside your saliva is many fresh samples of your DNA Genome. This is the unique genetic code that makes up.. well.. you! Unless you’re an identical twin, your DNA is completely unique to you in the entire world, and in the entire history of humanity.

Everybody knows that DNA looks kind of like a twisted ladder. The rungs of the ladder are the actual instruction sequence for your genome, and they come in 4 types called A, C, G and T. Sophisticated equipment breaks down the DNA sequence into a very long string of these letters. On its own, the sequence looks like complete gibberish, both to the average person and even to the scientists examining the data.

That’s where computer algorithms come in. Over many decades, through comparing hundreds of thousands of DNA samples and through exhausting trial and error, we have been able to identify patterns in the noise. There’s no string of letters that instantly means “Russian” or “Irish”, but we have noticed that confirmed Russian or Irish natives have very specific combinations of DNA letterings in certain spots of their genome. With computer help, if we then compare how close another DNA profile matches these specific strings, we can determine, with robust scientific accuracy, how much Russian or Irish descent that person has.

“The way that the algorithm works, it takes an entire genome and chunks it up,” said Robin Smith, who heads 23andMe’s ancestry program. “It takes little pieces, and for each piece, it compares it against British; it compares it against West African; it goes through the entire list, and it spits out a probability for [where that piece of DNA came from].”

The biggest weak point in this method is, the so-called “reference libraries” have to be accurate. Many people do have very accurate immediate background information that has been passed down from their parents. Other samples are pulled from independent research. But each company has their own private method for gathering these samples and matching incoming DNA profiles to them.

Where things get even more accurate is when it comes to Paternity Testing.

Researchers can track paternal ancestry by looking at the Y chromosome, which fathers pass to their male children. This time there’s no third-party “reference library” required, you just need to compare one set of DNA to another, and see if it matches up in enough key ways. Because your genome is 50% from your father, 50% from your mother, it won’t be a perfect match. But scientists know exactly what to look for to determine, with over 99% accuracy, the true identity of your father.

The Largest Accredited DNA Testing Network

DNA Paternity Testing provides rock-solid answers to important questions like parentage and ancestry. With over 2,000 centers nationwide, DNA Paternity Testing Centers is one of the largest, most affordable, networks of accredited DNA testing labs in the United States. Our price is unbeatable without sacrificing quality. We offer DNA testing for paternity, maternity and all other relationships (grandparents, siblings, aunts/uncles). Call us today at 866.232.7660 or ORDER ONLINE!

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