Identical twins can often be hard to tell apart and sometimes they may use this to their advantage, tricking everyone from parents to teachers or dates and pulling pranks. Not all twins look alike, with fraternal twins looking as dissimilar as brothers and sisters do.
Here are some more interesting facts:
Two babies to feed, two babies to change, double the diapers, double everything. Double duty is taken to a new level for moms of twins. According to a study published in the journal Proceedings of the Royal Society B mothers of twins have a longer life. Researches found that mothers of twins are physically stronger, to begin with. Giving birth to twins may be an evolutionary adaption when healthy moms take the opportunity to pass on double their genes in one shot.
Want to up your chances of having Twins?
As a women ages, she is more likely than her younger counterparts to have multiple births. A study published in the journal of Human Reproduction found that compared with women under 35, women ages 35 and older had a higher level of follicle-stimulating hormone and were more likely to release more than one egg in a menstrual cycle, according to WebMD.
Being tall increases your chances of having twins. Past research has found that taller women have more insulin-like growth factors that have been linked to both height and the rate of twins. Those who birthed two or more children were on average more than an inch taller than other mothers according to a study published in the Journal of Reproductive Medicine. In work published in Journal of Reproductive Medicine Dr. Gary Steinman an obstetrician at Long Island Jewish Medical Center, compared heights of 125 women who had twins and 24 who had triplets to the average height of U.S women.
Did you know that identical twins do not have identical fingerprints? Genes don’t tell the whole story of the ripples covering our fingertips; rather those ridges are influenced by random stresses experienced in the womb. Even a slightly different umbilical cord length changes your paw print.
The West African country of Benin has the highest national average of twinning, with a rate of 27.9 twins per 1,000 births.
In a remote town of Kodinhi, in Kerala (India), doctors are baffled and are trying to unravel the mystery of more than 220 twins born to just 2000 families.
Asia and Latin America have much lower twinning rates of about eight per 1,000 births, according to research published online Sept. 28, 2011.
While scientists aren’t certain why there are such differences in twin birth rates among the different regions of the developing world, they suspect most variations are due to the birth rates of fraternal twins. Identical twins seem to occur at a relatively constant rate of 3.5 to 4 per 1,000 births globally. Various factors, including a mother’s age, height, activities such as smoking, and whether she inherited any “twin genes,” which may be the cause of varying fraternal twin birth rates, researchers say.
Do Twins run in the Family?
Whether or not you will need to buy double of everything from cribs to car seats, may have more to do with chance than genetics, at least for identical twins. Scientists have yet to find any genes that cause a fertilized egg to split in two — resulting in monozygotic twins — suggesting identical double trouble is a random occurrence. And if you think just because your mother has a twin sister means there’s no chance for Baby A and Baby B in your delivery room, you may want to think again. Research has suggested that genetics is behind a woman’s propensity to release more than one egg at a time, which if two of the eggs are fertilized they become fraternal twins.
Even so, counter to conventional wisdom, fraternal twins don’t always skip a generation. According to an article in The New York Times, this notion may have to do with the fact that men who inherit this “twin gene” aren’t affected by it, but they can pass it onto their daughters who are more likely to have fraternal twins.
Great for Research
Science loves identical twins because they share some 99.9% of each other’s genes which makes them great subjects for researchers wanting to look at the differences between genetic factors and environmental ones. A test conducted by the Minnesota Twin Study of Adult Development looked at the aging process of both monozygotic and fraternal twins. Fraternal twins genes are only as similar as any two siblings but who tend to share the same environment. This study has helped to understand what causes individual differences in aging. Since the study began in 1986, they’ve found that our genes influence changes in our personalities and activity levels as we get older, with an active lifestyle contributing to more successful aging.
Wired to Be Social
Research shows that twins start to engage with each other as soon as 14 weeks gestation so it seems that twins are never really alone. Researchers from Umberto Castiello of the University of Padova in Italy studied the movement of 5 pairs of twin fetuses by using four-dimensional ultrasonography at the 14th and 18th weeks gestation. By 14 weeks, the fetuses were making movements specifically aimed at the co-twin, movements that increased between week 14 and 18.
For instance, in some of the videos, a fetus was caressing the back or the head of the co-twin. While self-directed movements, such as hand-to-mouth and hand-to-eye, decreased between the two tests, other-directed movements increased until they accounted for about 29 percent of observed movements at 18 weeks.
“These findings force us to predate the emergence of social behavior: when the context enables it, as in the case of twin fetuses, other-directed actions are not only possible but predominant over self-directed actions.