How similar is your genome to the genome of a random, unrelated person living on the other side of the Earth?
75 percent
80 percent
96 percent
99.9 percent
The correct answer and explanation is:
Correct Answer: 99.9 percent
The human genome is remarkably similar across all people, regardless of geographic origin. In fact, the genetic similarity between any two unrelated individuals on Earth is about 99.9 percent. This means that out of the approximately 3 billion base pairs in the human genome, only about 0.1 percent—or roughly 3 million base pairs—differ from one person to another.
This high degree of similarity arises from our shared ancestry as a species. Modern humans evolved relatively recently in evolutionary terms, and all current human populations descended from common ancestors who lived in Africa around 200,000 years ago. As humans migrated and spread across the planet, small mutations accumulated, but the overall genome remained highly conserved.
The 0.1 percent difference accounts for the genetic variation seen among individuals. These variations can influence traits such as eye color, height, susceptibility to diseases, and responses to medications. Some variations are single nucleotide polymorphisms (SNPs), while others involve insertions, deletions, or duplications of larger DNA segments.
This near-identical genetic makeup also emphasizes the unity of the human species. Genetically, there is more variation within a single population than between two different populations. For instance, two people from different parts of Africa may be more genetically distinct from each other than either is from someone in Europe or Asia.
Understanding the 99.9 percent genetic similarity has important implications in fields such as medicine, anthropology, and evolutionary biology. It reinforces the idea that race is not a biologically significant concept, but rather a social and historical one, since the genetic differences between populations are minimal and do not support distinct racial categories.