Fascinating facts about twins.

Think you know all about twins? Check your knowledge against this list of fascinating facts about twins.

1. A higher rate of twins (18-22%) are left handed compared to non-twins (10%).
2. Identical twins exhibit almost identical brain wave patterns.
3. Twins sometimes have their own language which only they can understand, this is called cryptophasia.
4. If the mother is herself a fraternal twin, the chances of having twins increases about five-fold.
5. Identical twins are sometimes born as mirror-image twins, meaning they are identical but their traits are reversed. For instance a left-handed twin would have a right-handed mirror-image twin.
6. Without the assistance of fertility treatments, twins occur naturally in 1 out of 80 births; triplets in 1 out of 8000; quadruplets in 1 out of 700,000; and quintuplets in 1 out of 65,610,000.
7. It is possible for fraternal twins to be conceived by two different fathers, a process known as super fecundation.
8. The scientific study of twins is known as "gemellology."
9. Twins do not have to be born on the same dates. The longest gap between birth is 85 days.
10. Once you've had fraternal twins, you are 3 to 4 times more likely to have another set!