Understanding the Science: How does recombination affect your percentages?

You’ve received your Living DNA results and are excited to see what you know about your family represented on screen. You log in and click on Recent Ancestry, but you don’t see the expected 25% Finland from your paternal grandmother, instead the percentage is much lower. What’s going on?

The first thing to remember in this situation is not to panic. This is actually a completely normal result.

You get 50% of your DNA from each of your parents - half from your mum and half from your dad. You’d think, then, that there would be 25% from each grandparent, 12.5% from each great-grandparent, and 6.25% from each great-great-grandparent. In fact, the 50% you receive from each of your parents is made from an entirely random selection of their own DNA.

It can be helpful to think of each grandparent’s DNA as being represented by a handful of different coloured sprinkles, so your mum gets 50 green and 50 yellow while your dad gets 50 purple and 50 blue.

When you were conceived, your DNA from each parent was randomly assigned - you’ll still have 100 sprinkles, but you could have got a different mix of sprinkles from each grandparent, you might end up with 30 yellow sprinkles, 20 green, 40 blue, and only 10 purple. This random assortment is why your DNA results might show a lower percentage from your Finnish grandmother than you anticipated.

This phenomenon is due to a process called “genetic recombination.” During recombination, the DNA from your parents mixes in a unique way before being passed to you. Some segments of your grandparents’ DNA might be overrepresented, while others might be underrepresented or even missing altogether. This is perfectly normal and is part of what makes genetic inheritance so complex and fascinating.

Now, you might be wondering - if this random assortment happens with everyone, does that mean my siblings could have different results from me? The answer is yes! Since DNA is shuffled during recombination, each sibling inherits a unique combination of their parents’ DNA. While you and your siblings share the same parents and grandparents, the specific mix of DNA results might look a little different.

For example, one sibling might inherit more DNA from a grandparent of Finnish descent, while another might inherit less. This can lead to siblings having slightly different percentages of ancestry from the same regions, which is a natural result of how genetic inheritance works.

The randomness in genetic inheritance isn’t just limited to your family - it also happens on a larger scale in nature, a process called “genetic drift.” Genetic drift refers to the random changes in the frequency of different genetic traits in a population over time. This process can cause certain traits to become more or less common in a population, independent of natural selection.

For example, in a small isolated population, a particular trait might become more common simply by chance, while another trait might disappear altogether. Over many generations, genetic drift can significantly impact the genetic makeup of populations, contributing to the diversity of life we see today.

Understanding your Living DNA results means recognising the natural variations in genetic inheritance. The lower percentage of Finnish - or any other region - from one ancestor doesn’t diminish their place in your heritage; it just means that their DNA wasn’t passed down to you in that perfect 25%, 12.5%, or 6.25% block.

These differences highlight the complexity of genetics and offer a clear picture of how unique your genetic makeup is. Your results provide you with personal insights into your ancestry, revealing the unique diversity within your family history.

If you have any questions, you can always reach out to our friendly support team by emailing help@livingdna.com. We'd love to hear from you!