1. Twins can have different biological fathers.
Each month, a woman releases one egg that can be fertilized by one sperm. However, there are times when two eggs are released, both of which could potentially be fertilized by separate male donors.
2. Separated twins have been known to live very similar lives.
Similarities that go beyond coincidental, such as marrying a woman with the same name, naming children the same, entering the same professions, and even falling ill at the same time have been reported by twins at high volumes.
3. If a pair of identical male twins have children with a pair of identical female twins, their children will legally be classified as cousins - but genetically they will be full siblings.
Since the genetic pool of identical twins is (not surprisingly) identical, if two sets of identical twins have children, those children have the same genetic makeup as their cousins.
4. Having twins could mean a longer life for the mother.
It is believed that women who give birth to twins are healthier than those who don’t, and that twins are an evolutionary adaptation to pass on the genes of those mothers twice in one pregnancy.
5. Taller women have a higher chance at giving birth to twins.
Countries with a taller than average ratio of women also have higher rates of births to twins. Taller people have higher levels of growth hormones, and in women this makes their ovaries more susceptible to spontaneous twinning.
6. Twins show signs of their bond in the womb.
According to an Italian study, twins begin reaching for the other as early as 14 weeks. By the 18th week, they touch the other twin more than themselves. Interestingly, the twins also gestured with and were delicate with each other.
7. Twins can be exact reflections of the other and are called Mirror Twins.
About 1/4 of twins wind up facing each other in the womb, and they become reflections of the other. One will be right handed where the other is a lefty, and birthmarks will appear on opposite sides of the body.
8. The belly button is the easiest way to tell twins apart.
Belly buttons are not genetic, they are scars left from removing the umbilical cord; and each one is slightly unique.
9. If a woman is a fraternal twin, she is more likely to give birth to one herself.
She is also much more likely to give birth to twins if she already has, or has a sibling who was a twin.
10. Even identical twins do not have identical fingerprints.
Even though they have identical DNA, fingerprints are formed by babies touching the amniotic sac, whose unique forms and ridges leave us with our individual fingerprints.
11. Twins are twice as likely to be left-handed than individually born people.
12. Twins can be born months apart.
Due to complications such as the water breaking prematurely, twins can sometimes be born weeks to months apart. The record for time between births of twins is thought to be 87 days, nearly 3 months.
