8 fascinating facts about twins

…belly buttons! Navels are scars from the detachment of the umbilical cord after birth, so they aren’t caused by genetics. Another way to determine who’s who: take fingerprints. Identical twins may share DNA, but exposure to different areas of the womb during development affects the fingertips’ ridges and whorls.

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Heteropaternal superfecundation occurs when a woman has sex with more than one man during ovulation. Sperm from each man fertilises an egg, resulting in twins. Though this phenomenon is common in dogs and cats, it’s extremely rare in humans.

The birthrate for twins has increased 76% since 1980, an uptick that some experts attribute to older women having children (women in their thirties are more likely than women in their twenties to have twins). Or maybe women are getting taller: A Long Island Jewish Medical Center study found that women who birth twins or other multiples were, on average, more than an inch taller than women who only birthed one child at a time.

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An extremely rare condition called superfetation occurs when a pregnant woman continues to menstruate and a second embryo forms. Often, the foetus conceived last is born prematurely, while the foetus conceived first is carried to term, but in some cases, the babies are born on the same day.

What sounds like kids’ babbling could actually be cryptophasia, a language developed between twins that only they can understand. Research published in the journal Institute of General Linguistics found that twin babies often use each other to learn vocabulary. The research estimates that up to 40 per cent of twins create a private language.

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When a fertilised egg splits later than usual, identical twins’ appearance and other traits can mirror each other. For example, one twin may have a birthmark on her left arm, while the other twin has a birthmark on her right or one twin may be right handed and the other left-handed. In extreme cases, one mirror-image twin’s organs may be reversed, with the heart on the right and liver on the left.

University researchers who studied birth and death records between 1800 and 1970 found that the mothers of twins tend to live longer than mums without twins.

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If you’ve ever seen newborn twins being bathed for the first time, it won’t come as a surprise to hear that twins may begin interacting the in womb as early as 14 weeks into a pregnancy.

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Source: RD.com