These twins look alike. But it turns out they might not be so identical after all.

These twins look alike. But it turns out they might not be so identical after all.

Scientists found that identical twin DNA can have tiny differences.

Scientists found that identical twin DNA can have tiny differences.

Identical twins Alf, front, and Sven Fehnhanhn pose with seven-month-old Luis Carl, front, and Albert Frank Millgramm during a twins’ meeting in Berlin, Germany. (AP/Jockel Finck)

Identical twins Alf, front, and Sven Fehnhanhn pose with seven-month-old Luis Carl, front, and Albert Frank Millgramm during a twins’ meeting in Berlin, Germany. (AP/Jockel Finck)

Twins John Reiff, left, and Bill Reiff are shown on their farm in Phoenixville, Pennsylvania. Some twins have up to 100 differences in their DNA. Others have only a few. (AP/Rusty Kennedy)

Twins John Reiff, left, and Bill Reiff are shown on their farm in Phoenixville, Pennsylvania. Some twins have up to 100 differences in their DNA. Others have only a few. (AP/Rusty Kennedy)

Jean Harrison, left, and Jane Umbarger look at a photo of themselves as babies. (Matthew Apgar/Northwest Herald/AP)

Jean Harrison, left, and Jane Umbarger look at a photo of themselves as babies. (Matthew Apgar/Northwest Herald/AP)

Not-So-Identical Twins

Posted: March 1, 2021

Have you ever met a set of identical twins? They may look exactly the same. But new research shows: Identical twins aren’t so identical after all—at least not in their genes.

What are genes? Think of them as information carriers. They tell your body to make you you. What color is your hair? Genes are made up of the DNA that decides that. How tall are you? Genetic material, DNA, determines that too. In fact, DNA designs every part of your body. So identical twins must have the exact same genetics, right? That’s what scientists thought—until now.

Scientists in Iceland studied DNA from 387 pairs of identical twins. They also studied DNA from the twins’ parents, children, and spouses. What did they find? “Early mutations that separate identical twins,” says geneticist Kari Stefansson.

A mutation is a teeny-tiny change in a sequence of DNA. It’s neither good nor bad. Identical twins start together as just one cell. But somewhere very early on, that one cell separates into two. Now there are two people! Those separate groups of cells continue to divide and grow. Scientists found that twin DNA could change slightly during this dividing. Some twins have up to 100 of these tiny differences inside their cells. Some have fewer.

These variations happen in only a tiny portion of each twin’s genetic code. But they might explain a lot. For instance, why is one twin is taller? Why does one twin have greater risk for certain diseases? Until now, researchers believed these kinds of differences didn’t come from genes. They thought they came from how the twins lived—what food they ate, who raised them, where they lived, and other factors.

All people are made in God's image. We’re connected to Him—and it shows all over us. Others can see God in us like you can see family resemblances. But we all bear the imprint of sin too. No one escapes that. Likeness to God is a gift—and Jesus takes away the sin that mars it.

“Behold, the Lamb of God, who takes away the sin of the world!” — John 1:29