What do ancestry tests really tell us?
It had only been a few months since my grandma passed away, but my grandpa felt it was important for me to take her prayer coins as my own—I had given them to her when I was just a kid, back when it seemed as though her multiple sclerosis was progressing past a point of no return. She carried those coins with her for another 13 years, right up until the day she died. Now, they’re mine to hold once again. Although worn down from years of anxious fidgeting, they have a resilient glint to them that’s hard to miss. They’re still the same coins, only now they have a distinct weight about them that can only be felt when holding a family heirloom.
The year I gave these coins to her was also the year that DNA sequencing captured the public’s imagination in earnest. In 2003, scientists from the Human Genome Project announced the publication of a nearly complete version of the human DNA sequence—all 3.2 billion base pairs. DNA sequencing had been around since 1965, but it had never achieved such a remarkable feat. In the years that followed, improvements to DNA sequencing technology made the process of reading a person’s DNA increasingly affordable.
Among the many applications of this technology, ancestry testing has been one of the most popular. By cataloging thousands of small patterns in your DNA, scientists can piece together your genetic ancestry and determine—with a fair amount of accuracy—where your ancient relatives may have lived.
Looking at the coins as they roll over one another in my hand, I can’t help but think about what else my grandma passed on to me and my siblings. Having studied biology for most of my adult life, I can confidently say that each of us inherited about a quarter of my grandma’s DNA. But what comes with that DNA? Family stories tell us that my grandma’s distant ancestors came to America from England. Could her DNA have passed on some English culture to our family, giving us a genetically determined “Englishness”?
It’s only in the past few hundred years that people have been able to move freely around the globe. For much of human history, people lived and died in the regions they were born in. Because of this, subtle characteristics—like the way someone talks or cooks—could spread within the confined space of a city or village until they became common traits among the people living there. In the same way that a single language can have regional dialects, the human DNA sequence can have subtle changes (or variants) that develop into patterns unique to specific geographical areas. These variants might affect what blood type a person has, how tall they grow, or the variants may have no effect at all. What’s important is that over thousands of years, in mostly isolated conditions, people living in the same area tend to inherit the same patterns of variants in their DNA.
Such was the case with all of our ancestors. Thousands of years ago, they mostly lived in isolated places. Patterns of variants in their DNA were passed down through generations until some of those patterns became more common in some populations compared to others. Today, we’ve inherited bits and pieces of those patterns. By analyzing your DNA, scientists can figure out what parts of the world you’ve likely inherited your unique set of patterns from.
So DNA tests can be a powerful way to look into the past and see where your family is from. If we look at my DNA, we’ll probably see patterns that indicate my ancestors—including my grandma’s—were likely living in England at some point. Genetically, I could be called part English. But does that also mean I’m culturally English?
No, it doesn’t. It’s true that segments of my DNA probably passed through England thousands of years ago, but a person’s cultural identity is much more than a few patterns in their DNA. As a society, we often use the same words when describing both a person’s genetic ancestry and their culture. But this can lead to a conflation of two dramatically different concepts.
Culture is an abstract notion that describes the collective norms and ideals that a person identifies with. It’s the food, the jokes, the stories, and the shared emotions that people may experience together. There are no clear lines dividing one culture from another. Far from it, cultures often overlap with one another and may even merge together with time. Importantly, a person’s cultural identity is molded by their personal experiences—meaning the culture they identify with can change over time.
In contrast, genetic ancestry is just the origin of those patterns in my DNA that ultimately give me clues about where my ancestors may have lived. It’s just a glimpse into the past. Those patterns can’t tell me what pranks my ancestors would pull on one another any better than the coins in my hand can. They can’t tell me what foods my ancestors liked, or what emotions they felt. In short, DNA can’t tell me about my culture, it can only tell me where my DNA has been.
This doesn’t mean my genetic ancestry is meaningless. Knowing where my DNA has been is like discovering many little genetic heirlooms that have been passed down from relative to relative for millenia. My grandma liked to travel, so one day, I’ll go to England—and elsewhere in Europe—to see where my ancestors may have lived. I want to see the hills my ancestors may have looked over, see the sun set from their vantage point, and taste the foods that have evolved in those regions. Their culture may not be mine, but rediscovering the genetic heirlooms in my DNA gives me a personal reason to go and learn about the cultures they lived in, and the cultures that grew out of theirs.
Helix is the leading population genomics and viral surveillance company operating at the intersection of clinical care, research, and data analytics.