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. It sounds like fraternal twins do indeed run in your family!
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.
A dad who's one of a twin may inherit the gene, but it won't increase his chances of having twins too, because the gene only affects ovulation. The same dad may pass on the gene to his daughter, who then goes on to get pregnant with twins, making it look like twins have skipped a generation .
But you may be left wondering: Can twins have different fathers? The answer is yes, but only in cases in which they're fraternal, as identical twins form from a single egg/sperm combination and thus cannot have different fathers.
They may share the same mother but different fathers (in which case they are known as uterine siblings or maternal half-siblings), or they may have the same father but different mothers (in which case, they are known as agnate siblings or paternal half-siblings.
The biological phenomenon of giving birth to twins with two different biological fathers is called heteropaternal superfecundation. In a rare and surprising event, a 19-year-old Brazilian woman gave birth to twins who belong to two different biological fathers.
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.
Everyone has the same chance of having identical twins: about 1 in 250. Identical twins do not run in families. But there are some factors that make having non-identical twins more likely: non-identical twins are more common in some ethnic groups, with the highest rate among Nigerians and the lowest among Japanese.
Identical twins are typically not hereditary like fraternal twins and occur in three to four births out of every 1,000 globally. A few families report a higher level of identical twins than expected, so there may be a genetic factor in rare cases. However, the cause of identical twins is typically unknown.
So if you, your mother or your maternal grandmother are or were fraternal (non-identical) twins then your chances of having twins may increase to as many as 1 in 7.
Do Twins Skip a Generation? If your father was a twin but you weren't, are you more likely to have twins? 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.
Originally Answered: Do you or know anyone who has a sibling who were born the same year, but aren't twins? That can be the case of what's called Irish Twins - two siblings born less than 12 months apart.
Although certain factors increase the chance of having twins, there is no way to improve the odds of having twins naturally. A woman will usually find out that she is pregnant with twins from an ultrasound early on in the pregnancy.
You're 35 or older
As you age, your chance of conceiving twins increases. Researchers have found that women over 35 produce more follicle stimulating hormone (FSH) than younger women, which may cause more than one egg to drop at ovulation.
Chimerism occurs when a woman is pregnant with twins and one embryo dies, and the other embryo absorbs the twin's cells. (Scientifically speaking, this type of chimerism is called tetragametic because the baby was derived from four gametes – one egg and one sperm for each embryo.)
Like twins, two fetuses eventually share the same womb and develop alongside each other. Both babies are usually delivered at the same time. Unlike twins, embryos from superfetation don't form during the same menstrual cycle. As a result, they're different gestational ages (in different stages of pregnancy).
An anonymous woman from Brazil has revealed that the twins she gave birth to have different fathers. The 19-year-old from Minerios, Goias, Brazil, who asked to remain anonymous, explained that when she took a paternity test to confirm who the father was, only one came positive for who she thought was the father.
The Dutch Twins are Kit and Kat, 5 years old and not yet big enough to be called by their real names, Christopher and Katrina. They live in a typical Dutch household, around the turn of the last century. The book follows their day-to-day adventures and accidental mishaps.
The term “Irish twins” refers to siblings who are born within 12 months of one another. This is especially true for children born in the same calendar year, or children who would be in the same grade of school. However, children born within 18 months of one another are still often referred to as Irish Twins.
It's technically possible for two siblings to be as close as 9 or 10 months apart. After your pregnancy comes to an end, you'll start ovulating again before you have your first postpartum period.
If one identical twin has autism spectrum disorder (ASD), the other twin has a 76 percent chance of also being diagnosed with it. The numbers are lower for fraternal twins. The percentage of fraternal twins who each share an ASD diagnosis is 34 percent for same-sex twins and 18 percent for boy-girl pairs, Dr.