Why do identical twins have the same DNA but still look different as they get older?
Quick Answer
Identical twins start with nearly the same genome because they come from one fertilized egg, but small DNA changes and epigenetic differences build up over time. These differences can affect appearance, health, and even behavior.
The Full Story
Identical twins usually begin life with almost the same genetic code because a single fertilized egg splits into two embryos. As they grow, tiny mutations can accumulate in different cells, and environmental influences can change how genes are switched on and off through epigenetics. Research comparing twin pairs has shown that these differences increase with age, especially in patterns of DNA methylation. That is why twins can become less alike in fingerprints, body shape, disease risk, and sometimes even personality traits.
Key Facts
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Suggested video title for this topic:
"Same DNA, different lives: how identical twins become less identical"
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