Amazing Facts About Twins

An obstetrician compared the height of women who gave birth to twins or triplets with the average height of women in the US, and found that taller women were more likely to birth twins. The research was published in the Journal of Reproductive Medicine.

The reason? Scientists suspect that it may be due to insulin-like growth factor, a protein that has been linked to both a higher percentage of birthing twins as well as increased height, as it stimulates the growth of some bone cells. Let’s take a closer look at some more amazing facts about twins.

Identical Genes, Different Personalities

Identical twins may have the exact same genes, but their personalities are often startlingly different—even when they were brought up in the same way. Researcher Tim Spector believes that this is due to environmental factors altering the expression of genes—a process referred to as epigenetics.

Even identical twins brought up in the same environment may deal with different life events, have different diets, or suffer from different illnesses. In fact, epigenetic variations may explain why one twin may get a disease such as breast cancer, while the other twin does not.

Twin mice also have different personalities since their surroundings play a role in influencing both their behavior and neural development, according to a study published in Science.

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Mirror-Image Twins

When a fertilized egg splits later in the embryonic stage than normal, mirror-image twins are the result. Some of their physical characteristics are typically reversed—hence the name ‘mirror-image.’ For example, one twin may be right-handed, while the other twin is left-handed, or they may have specific facial features such as moles or freckles on opposite cheeks.

Twins can speak their own language

Twins really do create their own languages, which are unintelligible to others. In fact, a study published in the Institute of General Linguistics suggests that autonomous languages exist in as many as 40 percent of twins, though they often do not last long. The language typically consists of some invented words, a few sound-based expressions and a variation of the language being modeled by adults. This phenomenon isn’t limited to twins, but can take place with close siblings of any stripe.

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Identical twins have different fingerprints

Although some of the whorls, loops and ridges are similar in the fingers of identical twins, the details are different, according to a review study published in Circulation Review. “Even twins that develop from one zygote occupy different positions in the womb, and the variations are enough to make a difference,” the New York Times explains.

More Twins Than Ever

The rate of twins is on the rise, according to research by the National Center for Health Statistics. The twin birth rate rose an astounding 76 percent from 1980 to 2009. Only one in every 53 babies born was a twin in 1980, but this has increased to one in 30 in 2009.

The biggest factor? Infertility treatments, which increase the rate of twins, account for a majority of the increase. In addition, women who are over the age of 30 are more likely to give birth to twins, and the number of women in that age bracket giving birth has increased.

Dogs can differentiate between twins

Although it’s difficult for humans to differentiate between identical twins, this isn’t the case for specially trained German Shepherds, who can pick up on scent variations between both identical and non-identical twins. This is true even if the siblings ate the same food and lived in the same house. The dogs used in the study were trained police dogs that were specifically used to identify scents in line-ups. The research was done on twins over the age of five; it is unclear whether identical twins younger than that would have scents too similar to differentiate.

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