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Identical Twins Are Not Identical

There is a common parental misunderstanding that arises when the term “identical twins” is paraded around. Identical twins are known scientifically as “monozygotic twins.” This Scrabble winner of a term refers to the fact that these types of twins arise when a single sperm fertilizes a single egg to form a zygote, and this zygote goes on to split into two masses of cells that give rise to the twins. By contrast, fraternal twins are essentially regular siblings that are born at the same time. One sperm fertilizes one egg and another sperm fertilizes another egg at the same time and bingo: fraternal twins.

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Featured

 Why do identical twins end up having such different lives?

Their genes are exactly the same, so why don't identical siblings' lives follow more similar patterns? The scientist behind a pioneering 21-year study believes he has the answer.

Articles of Interest

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Our study showed that it can have considerable impact on a twin’s physical and mental wellbeing.

How Can Identical Twins Turn Out So Different?

Scientists used to think that identical twins turned out differently because they were treated differently — by friends or teachers or their parents, Turkheimer says. So about a decade ago he started looking for scientific evidence of this, and didn't find much. So he started asking himself, "How do you explain it? How do they get different?"

How do identical twins happen?

Luck needs to be on your side. Identical twins do not run in families and can happen for any couple with any pregnancy. Non-identical twins are influenced by genetics; women whose mothers or grandmothers had non-identical twins do have more chance of having non-identical twins themselves. But identical twins are just random.

Identical Twins Accumulate Genetic Differences in the Womb

DNA replication errors during cell division cause monozygotic twins to diverge from each other even during the earliest stages of development, a new study finds.

Identical Twins Aren’t So Identical – Which Makes Twin Studies Harder

As twins grow and develop, each will acquire his or her own set of mutations - which could throw a wrench into twin studies.

Identical twins carry genetic modifications no one else has

Distinctive pattern of chemical tags could reveal how twinning happens, lead to a test for “vanishing twins”.

Identical Twins Hint at How Environments Change Gene Expression

Studying twins has long offered insight into the interplay of nature and nurture. Epigenetics is the next frontier.

Identical Twins' Genes Are Not Identical

Twins may appear to be cut from the same cloth, but their genes reveal a different pattern.

Many Identical Twins Actually Have Slightly Different DNA

In a new study of over 300 pairs of identical twins, only 38 had perfectly identical DNA.

Scientists can now tell if you had a ‘vanishing’ twin in the womb

New research hints at why some twins are identical.

Some identical twins don’t have identical DNA

Mutations arising early in development may account for genetic differences.

Twins can become ‘unidentical’—and more fascinating twin facts

Looking into how twins’ genetics work can give researchers new insights into how different lifestyles and habits affect two people with the same genetic blueprint.

What’s So Frightening About Identical Twins?

“The Silent Twins,” a new film starring Letitia Wright and Tamara Lawrance, sets out to show the complexity of twinship onscreen.

Why are there differences between identical twins?

Even identical twins, who are meant to have identical DNA, differ somewhat in appearance and are not the same in terms of height, physical makeup, disease profile and the like. Why is this so?

Why Identical Twins Are a Nightmare for the Legal System

Twins have been acquitted of everything from dangerous driving to a Hollywood-style heist, and they continue to cause havoc in courtrooms.

Why Identical Twins Don't Always Look the Same

But, actually, twins who start out with identical DNA always have slightly different DNA by the time they're born. And they also each use their DNA a bit differently too. Even though this is true for all identical twins, we can’t usually tell because the changes happen in parts of the DNA that don’t affect how identical twins look. Which isn’t surprising. DNA is large and very little of it has to do with, for example, skin and eye color.

Resources

10 Questions You Always Wanted to Ask Identical Twins

What's it like to constantly be around another human being who's just like you? And have you ever slept with the same person?