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.
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.
To form identical or monozygotic twins, one fertilised egg (ovum) splits and develops into two babies with exactly the same genetic information. To form fraternal or dizygotic twins, two eggs (ova) are fertilised by two sperm and produce two genetically unique children.
Fraternal twins are, essentially, two ordinary siblings who happen to develop in the womb together and who are born at the same time, since they arise from two separate eggs fertilized by two separate sperm, just like ordinary siblings.
However, for a given pregnancy, only the mother's genetics matter. Fraternal twins happen when two eggs are simultaneously fertilized instead of just one. A father's genes can't make a woman release two eggs.
Yes, some types of twins are hereditary, meaning that twins run in families. Heredity on the mother's side ups a couple's odds of conceiving fraternal twins. Fraternal twins are two babies from two different eggs that were released from the ovaries simultaneously.
Factors that increase the chance of twins include: consuming high amounts of dairy foods, being over the age of 30, and conceiving while breastfeeding. Many fertility drugs including Clomid, Gonal-F, and Follistim also increase the odds of a 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.
In some instances, the dead twin is compressed into a flattened, parchment-like state known as fetus papyraceus. Vanishing twins occur in up to one of every eight multifetus pregnancies and may not even be known in most cases.
It is likely that twins' awareness of one another starts sooner than seven or eight months of age. An article by the late doctor, T. Berry Brazelton, observed that at age three to four months, an infant identical female twin seemed disoriented when her sister was removed from the room.
Young twins are together nearly all the time, and like any two people who spend most of their time together, they learn to rely on nonverbal or shorthand forms of communication. They're able to act intuitively, understanding each other's gestures, grunts, or vocalizations.
40% of twins invent their own languages. Identical twins have different fingerprints. Twins can have completely different skin tone. Twins start interacting in the womb at 14 weeks.
What happens when one twin absorbs another? The vanishing twin's tissue gets absorbed by the surviving embryo(s) and the parent, too. This absorption process is completely harmless.
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).
In the case of pregnancy continuation, the dead twin will progressively transform into “fetus papyraceous” due to the absorption of the soft tissues, placental and amniotic fluids. The dead fetus will be found compressed between the amniotic sac of the survival twin and the uterine wall [3].
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.
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.
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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.
Do Twins Skip Generations? Many people believe twins skip a generation, but that's just a myth. The idea that twins skip generations likely comes from the fact that the genetic factors contributing to twins only come from the gestational parent's side.
Heteropaternal superfecundation is an extremely rare phenomenon that occurs when a second ova released during the same menstrual cycle is additionally fertilized by the sperm cells of a different man in separate sexual intercourse.
Dizygotic (DZ) twins, also called fraternal twins, occur when two egg cells are each fertilized by a different sperm cell in the same menstrual cycle. DZ twins are about twice as common as MZ twins, and they are much more likely to run in families.
Vanishing twin syndrome, as the name depicts, is a condition in which one of a set of twins or multiple embryos dies in utero, disappear, or gets resorbed partially or entirely, with an outcome of a spontaneous reduction of a multi-fetus pregnancy to a singleton pregnancy, portraying the image of a vanishing twin.