Along with the ‘better’ half, there’s also the phenomenon of the ‘other’ half. For better or for worse, some of us come into the world complete with a spitting image of ourselves.

Mary Kate and Ashley Olsen may be the world’s most famous twins, but there are many other celebrities like Scarlett Johansson, Keifer Sutherland, Vin Diesel and Ashton Kutcher, who have twin siblings.

But there’s a thing or two about twins that may surprise you.

1. You can tell them apart from their belly buttons. Even identical twins have different shaped navels because navels have nothing to do with genetics, they’re scars from the severing of the umbilical cord. Of course, another way of identification is fingerprints. Every human being has a unique set of prints on their fingers, even twins.

2. Twins can have two different fathers. Rare, but it happens. Heteropaternal twins are a biological reality, conceived when a woman has sex with two different men while ovulating. Remember the Arnold Schwarzenegger and Danny DeVito film ‘Twins’? Well, life is stranger than fiction!

3. Twin births are on the rise. The world may soon have more twins than ever before. There’s been a 76% increase in the birthrate for twins since the year 1980. The spike could be because women are opting for motherhood later in life. Research shows that women in their 30’s have a higher chance of conceiving twins than those in their 20’s.

4. Twinspeak is an actual language. Research published in the Institute of General Linguistics shows that twins develop a different ‘vocabulary’ from single babies, picking up sound patterns from each other. It’s estimated that around 40% of twins create a private language to communicate with each other. Twin-language even has a scientific name; it’s called ‘cryptophasia’.

5. Twin bonding begins early. As early as 14 weeks into pregnancy, twin babies begin to interact with each other, creating a sibling-bond that’s stronger than that of children born separately. That’s why twins can often easily read each other’s minds, and react to things in a similar manner.