It's a common misconception that twins skip a generation in families. There is absolutely no evidence, other than circumstantial, that twins are more likely to occur every other generation.
According to conventional wisdom, twins not only run in families, but they also — for some strange reason — always skip at least one generation.
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.
A lot of people wonder what their chance is of having twins. You might have heard that twins “run in families”. And that can be true! Compared with the general population, women with a mother or sister who have had twins are twice as likely to have twins themselves.
It's not unheard of for a twin pregnancy to go undetected in early ultrasounds (say, around 10 weeks). But once you reach the midway point of your pregnancy and have your 20-week anatomy scan, you can be 99.99 percent confident about how many babies to expect at your delivery.
The baby's heartbeat can't usually be detected before about 7-8 weeks, but some scans are performed before this. If one of the tiny twins happens to be hidden behind the other when the scan is performed, then there might not be any clue that you're carrying more than one baby.
According to The American Society for Reproductive Medicine, women who are fraternal twins have a 1 in 60 chance of having twins, and men who are fraternal twins have a 1 in 125 chance of fathering twins. It was previously believed that identical (monozygotic) twins were random — not genetic.
This is why fraternal twins run in families. However, only women ovulate. So, the mother's genes control this and the fathers don't. This is why having a background of twins in the family matters only if it is on the mother's side.
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.
For a given pregnancy, the odds of conceiving fraternal twins are only determined by the mother's genetics, not the father's.
This belief is based on the assumption that twinning is genetic and runs in families. However, if that was truly the case—if there was a twin gene—then twins would occur with predictable frequency in those families that carry the gene. There is no concrete scientific evidence that suggests twins skip a generation.
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.
Identical Twins
It's not based on family history or genetics. Identical twins form when a single fertilized egg splits and forms two embryos. Now in this case, it's not because of mom or dad. It's just beautiful luck that creates identical twins.
Medically, this 7-year defect is very rare. Twins are typically born with a bit of a delay — a few minutes to a few hours. Some even have separate birthdays, due to being born just before and just after midnight. The Zeitgest girls were not only born 7 years apart, but Ms.
Twins (non-identical) can be born at completely different times, sometimes even years apart.
According to Guinness World Records, the longest confirmed interval between the birth of twins is 90 days. Fraternal twins Molly and Benjamin West were born on Jan. 1 and March 30, 1996, in Baltimore.
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.
Identical twins have 100% of their DNA the same while fraternal twins share only 50%. But what about semi-identical twins? Well, they have 75% of their DNA the same.
Is there a third type? Traditionally, the science around twins has taught that identical and fraternal are the only two types. But a third type might exist, called polar body or half-identical twins.
For women born 1870-1899, moms of twins averaged reproductive spans of 14 years 11 months versus 14 years for singleton moms. Both results were statistically significant. Moms of twins also were older at the time of their last birth.
Recognizing a parent's face is one of the most important early skills babies learn. So when one of the parents has an identical twin, it's a recipe for confusion.
They found that twins at first birth were linked to higher divorce rates at 13.7% compared to 12.7% for singletons. The link was statistically higher among moms attending college at 14.4% with twins vs. 10.5% with single births.
Fraternal twins — the most common kind of twins — occur when two separate eggs are fertilized by two different sperm. Each twin has his or her own placenta and amniotic sac.
Most often, fetuses known in utero as twin A are also first born and thus retain their label. However, this is not always the case, such that the twin A newborn was previously labeled twin B in utero and vice versa.
Identical twins will always have the same blood type because they were created from the same fertilized egg (fraternal twins can have different blood types — again, providing the parents do — because they are created by two fertilized eggs).