Do Identical Twins Have The Same DNA

Have you ever come across two people who are the spitting image of each other? For centuries, scientists and the public have been fascinated by their striking resemblance. Though identical twins appear to be exact, the question remains: Are identical twins similar in terms of their DNA?

When people see twins who look exactly alike, they automatically conclude they had to share 100% of their genetic makeup. Is this a scientific assumption entirely correct? In this case, let’s peek into this fantastic topic by answering a few common questions around twin genetics.

Are identical Twins Truly Identical?

First, identical twins are superficially perfect genetic copies of each other. Suppose a single fertilised egg splits into two embryos early in development. As this happens, they will develop into two individuals, both with the same genetic foundation. No, this is not fraternal twins, two eggs triggered by different sperm cells, giving them only about 50% of DNA as regular siblings.

Are There any Genetic differences in Identical Twins?

Even though identical twins do begin with almost similar DNA at conception, research has proven that genetic differences can occur over time. One study published in 2021 in Nature Genetics found that the average number of early developmental mutations that identical twins differ from one another is 5.2 (Jonsson et al., 2021). All these minute differences in genetics tend to accumulate throughout life due to the environment and random mutations. 

How do Identical Twins develop Genetic Differences?

Despite the identical twins starting with the same DNA code, various processes can contribute to making them different, including

• After the embryo splits, some random mutations occur first. Since these mutations take place after the twins have already split apart, the twins do not share the same.
• Second, that signs can change how genetic facts are expressed through a method called epigenetics. Chemical markers that switch genes on or off may be different in the twins, for example, as they grow older and live in various environments.
• Third, unlike any other pair of twins, each pair builds up more and more distinct genetic changes in some of their cells as they grow older.

 These are not always characteristics of all cells, but are a part of making up genetic differences.

Can Identical Twins have Different Physical Features?

Twins can differ slightly in appearance, sometimes even glaringly, even though their DNA is nearly identical. Your babies may be different from one another. 

• One twin might be taller than the other
• One may have a different birthmark
• Or have health conditions that the other does not.

Why do Physical Differences occur in Identical Twins?

Many of these differences are due to changes in the core DNA sequence. These occur due to environmental factors rather than to differences between the core DNA sequences.

For instance, one twin is exposed to different amounts of sunlight, various nutrients, or other stressors. This will impact the way their genes are expressed and become visible over time.

Fingerprints are among some traits that are unique for every person, and never are the same for twins. 

Twins also touch different parts of their surroundings even before being born and leave behind ridge patterns on their tiny fingertips.

Conclusion

Face DNA Testing offers specialised twin testing services, such as determining whether twins are identical or fraternal. Given that face DNA testing can do more than the standard twin zygosity test, we can also conduct advanced genetic analysis to determine the minute differences between identical twins for purposes such as forensic research and personal medical counselling.

Twin genetics is a continuing science, and we have learned that even the most identical twins are different genetically. Even when it comes to nature’s gift of their exceedingly similar genetic base, which results in their uncanny likeness, once again, nature ensures that no two humans, not even identical twins, are quite alike at the DNA level.