Sunday, April 15, 2018

Differing DNA Ancestry in Siblings

     You are taught throughout your life that "blood is thicker than water". Meaning that no matter what, your family will always be there. Because you are closer to them than anyone else in life. However, this may not actually be the case. According to recent studies, biological siblings may actually have less in common with one another than they might think. In one study two siblings, Kat and Evan Abraham, used a genetic ancestry test to determine their ethnic background. While expecting the results to be similar, they received the opposite in some cases. Kat was found to be 13% genetically related to Italy and Greece. While her brother Eddy was 23%. In another similar study, six  complete strangers had roughly the same genetic ancestry according to National Geographic's Geno 2.0 DNA kit.

     Biological siblings can have differing genetic ancestry based on a variety of reasons. DNA shuffle is the slight variations inside of an egg and sperm's DNA. This variation comes from the genetic recombination of DNA. After this shuffling of genetic material, the resulting sperm and egg have their own specific combination of genes. Meaning that each offspring will inherit slightly different DNA from each parent. One can take DNA testing with a grain of salt. As these genetic ancestry tests only compare the incoming DNA material with the samples in the database. And the majority of the samples come from North America and parts of Europe. Resulting in the data from other places to be less specific.

     I myself have a younger brother. This information makes me wonder how similar our genetic ancestry is. All my life i have believed we are incredibly similar. This newfound knowledge on genetic ancestry makes me question myself and the person I call my brother.

Article Link:
Six Strangers Link:
Info on National Geographic's Geno 2.0 Kit:


  1. This is really interesting to think about! I wonder how many studies have been done to prove this idea. I feel like some siblings look exactly alike while others look very different. Therefore, that leads me to believe that siblings can have a lot of different genetic relationships.

  2. This article is very interesting because I have 3 brothers and I look very similar to one and completely different compared to my youngest brother. I have tan skin and no freckles and he is very pale with many freckles. This makes me curious how much more genetically different I am with this brother than my other brothers.

  3. Recently my sister did a DNA ancestry test and got back her results and we both assumed that those results would match mine. But after taking this genetics course and reading this article, it reminds me that no two people are identical. Even though we are extremely alike, I am curious how we are different.