Twins Are Multiplying(01 of20)
Open Image ModalNope, you don’t need an eye exam — you really are seeing double. According to a recent CDC report, the birth rate for twins has increased a whopping 76 per cent since 1980.In fact, one in every 30 babies born in 2009 was a twin (compared to 1980, when the rate was one baby in every 53). What’s with the binary-baby boom? One factor contributing to the upsurge: The age of mothers has trended up over the years, and a woman in her thirties is more likely to have twins than someone in her twenties, according to the study’s lead author, epidemiologist Joyce Martin, MPH. However, while age is an independent risk factor for twins, it also tends to correlate with increased use of fertility treatments, which was likely the biggest contributor to the spike in twin births. (credit:Shutterstock)
Yep, There's a ‘Twin Gene’(02 of20)
Open Image ModalKnow any families with multiple sets of multiples? There may be a scientific explanation behind all that multiplying — hyper-ovulation.If a woman inherits a certain gene that causes her to hyper-ovulate (meaning she’s more likely to release multiple eggs during ovulation), her chance of having fraternal twins — which are produced from two separate eggs — increases. And since that gene is, well, genetic, parents may also pass it on to their kids, making it possible for twins to run in the family (and perhaps even for twins to have their own little sets of twins). However, there’s no known gene linked to identical twins — which results when one egg splits in half — so this twin type isn’t hereditary.And what about that long-held idea that twins tend to skip a generation? According to an explanation in The New York Times, the theory may have gotten its roots since only women are affected by the hyper-ovulation gene (since men don’t ovulate) — but men can in fact pass it on to their daughters (hence, seemingly “skipping” a generation). (credit:Shutterstock)
Twins Can Be Born Years Apart(03 of20)
Open Image ModalTwins Can Have Different Dads — and Be Different Races(04 of20)
Open Image ModalSome Twosomes Speak ‘Twin Talk’(05 of20)
Open Image ModalTwins Start Bonding in Mom's Belly(06 of20)
Open Image ModalNo wonder twins share such an unbreakable bond — they get a head start on the rest of us.Researchers from University of Padova in Italy recently studied 3D ultrasound videos of five sets of twins in the womb. When the fetuses were just 14 weeks old, the researchers noticed that the pairs seemed to be reaching out for each other, touching head to head and arm to head. At 18 weeks, they were stroking each other more often and were in physical contact about 30 per cent of the time. Even more phenomenal, the fetuses seemed to be extra gentle when touching around their siblings’ eyes (likely because this area is so delicate, the researchers posit). (credit:Shutterstock)
There's a Twin-Inducing Diet(07 of20)
Open Image ModalWant to have twins? Stock up on cheese and start chugging milk.According to a study published in the Journal of Reproductive Medicine by Gary Steinman, MD, PhD, an ob-gyn at Long Island Jewish (LIJ) Medical Center in New Hyde Park, N.Y., women who consume dairy products may increase their chances of conceiving twins. When Dr. Steinman looked at the twin birth rates of vegans (who don’t eat any animal products, including dairy) compared to non-vegans, he discovered that the latter group was five times more likely to have two little bundles of joy. (credit:Shutterstock)
One Brazilian Town Is Booming With Multiples(08 of20)
Open Image ModalThe small South American town of Cândido Godói may just be the twin capital of the world. From 1959 to 2008, a whopping 8 per cent of births in São Pedro (one of the town’s villages), resulted in twins — compared to less than 1 per cent throughout the rest of the country. (credit:Shutterstock)
When Twins Are Separated at Birth, Scientists Pay Attention(09 of20)
Open Image ModalThanks to the whole “nature vs. nurture” debate, twins who get separated at birth receive a whole lot of attention from researchers (would they have the same values? Health habits? Psychological patterns?). But because you can’t just split up twins in the name of science, very few studies have been able to track twins who live completely separate lives. (credit:Shutterstock)
Identical Twins Aren't Exactly Identical(10 of20)
Open Image ModalThey come from the same egg and look so similar it can be impossible to tell them apart — but anyone who knows a set of identical twins knows that not they’re actually carbon copies of each other. And researchers are continuing to discover why identical twins aren’t quite as indistinguishable as once thought. (credit:Shutterstock)
The World's Oldest Twins (11 of20)
Open Image ModalThese Celebs Have Less-Famous Twins(12 of20)
Open Image ModalHunter Johansson (left). Michael Kutcher. Patricia Bundchen.Ever heard of them? Probably not — but we’re willing to bet you’re familiar with their fraternal twin siblings, Scarlett, Ashton, and Gisele.And these celebrities aren’t the only ones with other halves: 24’s Keifer Sutherland has a twin sister named Rachel; Jon Heder of Napoleon Dynamite has an identical double, Daniel; and Alanis Morissette shares a birthday with her brother Wade.Who knew? (credit:Getty)
Mums Living Longer?(13 of20)
Open Image ModalAfter digging up the birth records of more than 59,000 women between 1800 and 1970, University of Utah researchers found that mums of twins tend to live longer than mums without twins.
More Than Just Two Types (14 of20)
Open Image ModalThere are more than just fraternal and identical twosomes; other rare twin types include “half identical twins” (when the egg splits and then each half is fertilized) and mirror image twins (identical twins who develop asymmetrically). (credit:Shutterstock)
Unique DNA(15 of20)
Open Image ModalIdentical twins don’t have identical fingerprints. (credit:Shutterstock)
Morning Sickness (16 of20)
Open Image ModalMums who are expecting two tend to have higher levels of morning sickness, likely because of increased levels of the hormone human chorionic gonadotropin (HCG).
A 6th Sense? (17 of20)
Open Image ModalSolving The Mystery (18 of20)
Open Image ModalUsing an ultrasound isn’t the only way doctors can detect a twin pregnancy — some figure it out when they hear two tiny heartbeats through their stethoscope. (credit:Shutterstock)
Double And Trouble (19 of20)
Open Image ModalGaining The Pounds (20 of20)
Open Image ModalMums-to-be expecting one child tend to gain 25 to 35 pounds during pregnancy. But if you’re pregnant with twins? You can expect to gain a whopping 35 to 45 pounds. (credit:Shutterstock)