The results suggest that twin fetuses are aware of their counterparts in the womb, that they prefer to interact with them, and that they respond to them in special ways. Contact between them appeared to be planned—not an accidental outcome of spatial proximity, says study co-author Cristina Becchio of Turin.
It's no surprise there's a special bond between twins, but did you know that it begins in the womb? A 2010 study from researchers at Italy's University of Parma and University of Turin found that twins interact socially with each other as early as 14 weeks in the womb, according to Scientific American.
Twins start interacting in the womb at 14 weeks. Identical twins can develop different diseases. It is possible for twins to have different dads. Once you have one set of non-identical twins, you are 3-4 times more likely to have another set.
Fraternal – nonidentical – twins develop from two separate fertilized eggs. By 6 weeks, their hearts are beating, and at 8 weeks all of their major organs start developing. The twins' faces take shape, with closed eyelids, at 12 weeks, and at 16 weeks their sex organs are apparent.
Twins start to bond in the womb. They learn how to share nutrients and start to reach out to each other as they grow and develop. They grow in separate amniotic sacs and have separate placentas. They cannot physically reach out to each other, but they can feel each other in the womb and give each other some nudge.
Now a study suggests that the propensity for social interactions exists in the womb. Twins begin interacting as early as the 14th week of gestation.
Fraternal twins, in which each of two eggs is fertilized by a different sperm cell, occur in about four of every 1000 births. About half of those result in male-female twin pairs.
A little more than half of twin pregnancies end in preterm delivery (before 37 weeks). While 40 weeks is the full gestation period of the average pregnancy, most twin pregnancies are delivered at approximately 36 weeks (range 32-38 weeks depending on the type of twin pregnancy).
The quick answer to this question is that, in a twin pregnancy, it is the mother's genes that determine twins. First up, giving birth to identical twins is not genetic, but conceiving fraternal twins is. The mother may have the genetic trait of releasing two eggs in one menstrual cycle.
Around two in three sets of twins are fraternal. Two separate eggs (ova) are fertilised by two separate sperm, resulting in fraternal or 'dizygotic' (two-cell) twins. These babies will be no more alike than siblings born at separate times.
The hardest thing about having twins is...
“Managing the movement of two babies. Carrying them both up and down the stairs, getting them into the car, etc.” —Simeon R. “Often having to make one baby wait!” —Catharine D. “Being outnumbered—the logistics of two on one is definitely the hardest.
Identical twins share a particularly intense bond. They are the result of one fertilized egg splitting into two, giving them identical DNA. (Fraternal twins are the result of two separate, genetically different fertilized eggs.) As a result, identical twins are as close as two people can be.
Conjoined twins are caused by two embryos that are joined together during fertilization, resulting in twins that are physically connected, most commonly at the abdomen, chest or head.
The signs of a twin pregnancy are different for everyone, but typically include heightened normal pregnancy symptoms. Common signs include more severe nausea, earlier weight gain, intense fatigue and increased appetite.
When twins are born with their bodies connected, they are called conjoined twins. Some twins share only a small amount of tissue, and both children may have all the organs and other structures they need. Usually, the connection is more complex.
According to the Office on Women's Health , women who are aged 30 years or older are more likely to conceive twins. The reason for this is that women of this age are more likely than younger women to release more than one egg during their reproductive cycle.
Identical, or monozygotic (MZ), twins have 100 percent of their genes—including those that influence risk for alcoholism—in common, whereas fraternal, or dizygotic (DZ), twins share (on average) only 50 percent of the genes that vary in the population (see figure). Common Environmental Sources.
What is the likelihood of having more than one set of twins? If existing twins are identical the chance of having another set is the same as most women, about 1 in 250. If the twins are non- identical the chances of having twins again are much higher.
In fact, one British study tested ESP potential among identical twins and found that they were correct about 25% of the time, the same as any other siblings. There is one particular power though which twins possess, longevity. Fraternal twins live longer than singletons and identical twins longer still.
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That's not all, Monga says. Women pregnant with twins complain of more back pain, sleeping difficulties, and heartburn than those who are carrying one child. Being pregnant with twins also carries a higher rate of maternal anemia and a higher rate of postpartum hemorrhage (bleeding) after delivery.
They come from the same fertilized egg and share the same genetic blueprint. To a standard DNA test, they are indistinguishable. But any forensics expert will tell you that there is at least one surefire way to tell them apart: identical twins do not have matching fingerprints.
If twins are a boy and a girl, clearly they are fraternal twins, as they do not have the same DNA. A boy has XY chromosomes and a girl has XX chromosomes.
They're also more likely to have health problems later in life, like high blood pressure. More than half of twins and nearly all higher order multiples weigh less than they should at birth.
It's equally unsurprising that a Danish study found that twins are less likely to get married than non-twins. As twins have a partner from birth, the study suggests that they may not have the same desire for marriage as singletons.