Many parents eagerly anticipate their first ultrasound, as it allows them to catch a glimpse of the new baby they have already developed a deep attachment to.
They sit there with sweaty palms as the ultrasound technician begins scanning for the baby, but then they get the words that bring shock to a lot of new parents: It’s twins!
Now there is an unexpected baby in there to love. Parents typically have tons of questions after absorbing the initial shock. Identical or fraternal twins? Will I be able to tell my babies apart? How different or how close to the same can they actually be?
Although early ultrasounds cannot tell if the twins will be identical or fraternal, genetics may be able to assist in answering some of these questions.
Are twins more likely to have twins? A fraternal twin is more likely to conceive fraternal twins. This is the result of genetics leading to an overstimulation of the hormone that controls egg production, leading to more than one egg being released. An identical twin is no more likely than anyone else to give birth to twins.
Several factors can play into whether or not you will have twins, but it goes deeper than that. There is a difference between conceiving fraternal twins and identical twins. Fraternal twins are dependent on genetics and hormones.
Identical twins are nothing more than the luck of one fertilized egg splitting into two separate fetuses. There is no evidence of any genetic or lifestyle differences that will increase a woman’s chance of having identical twins.
Fraternal Twins’ Odds of Having Twins
Since having fraternal twins is based solely on genetics and hormones, it is more likely for a fraternal twin to have twins than a woman who is not a fraternal twin due to the hereditary factors that come into play.
How Are Fraternal Twins Conceived?
Fraternal twins are conceived when two separate eggs released from the mother meet two different sperm cells from the father. Typically, a woman only releases one egg that meets one sperm cell from the man for a singleton pregnancy.
Are Fraternal Twins Hereditary?
Fraternal twins are hereditary. Fraternal twins are the direct result of hormones. If a woman’s body overproduces certain hormones, the result is the release of more than one egg.
The release of more than one egg (known as hyperovulation) could lead to the fertilization of both eggs resulting in a pregnancy with twins. Genetics plays a big role in how a woman’s body handles hormone production.
Scientists are linking hereditary genes that increase a woman’s chance of having fraternal twins. One of the genes specifically has to do with how a woman’s body produces the follicle-stimulating hormone that helps with the release of more than one egg.
Another hereditary gene controls how the body responds to the overproduction of the follicle-stimulating hormone. Both genes could be passed on from generation to generation.
Chances of Having Fraternal Twins
The chances of conceiving twins depend on several factors, including a woman’s age, genetics, weight, and even height.
Women over the age of 30 have an increased chance of having twins due to the rise in the production of the follicle-stimulating hormone as age increases.
If fraternal twins run on the mother’s side of the family, she will have an increased chance of conceiving fraternal twins, and if there is a history of fraternal twins on both the mother and father’s side of the family, then chances are much higher.
Chances of Having Twins Again
Studies show a woman who has had one set of fraternal twins is three times more likely to have a second set of twins than a woman who has had a previous singleton pregnancy.
The reasoning behind this comes from the fact that the woman may have a hereditary condition that causes her to release multiple eggs during a single menstrual cycle resulting in the possibility of having more than one set of fraternal twins.
In addition, in a woman who has already had one set of twins, the uterus is more likely to be able to stretch to accommodate more than one baby, resulting in a high chance for a healthy twin pregnancy.
Is a Fraternal Twin More Likely To Have Twins?
A woman who is a fraternal twin has a 1 in 60 chance of having twins, compared to a singleton woman who has a 1 in 250 chance of naturally having twins. A man who is a fraternal twin has a 1 in 125 chance of fathering twins.
Identical Twins’ Odds of Having Twins
Fraternal twins may be more likely to have twins due to genetics, but the same can not be said about identical twins.
How a woman’s hormones are regulated and menstrual cycle tendencies can be passed down from generation to generation, thus leading to the increased odds of fraternal twins.
Since identical twins are not the result of any hormones or genetic factors, an identical twin is no more likely to have twins than any other woman.
How Are Identical Twins Conceived?
Identical twins are conceived as one egg and one sperm cell that is then divided into two, creating two fetuses who share the same DNA. The reason why an egg would split is unknown and can only be explained as luck.
Are Identical Twins Hereditary?
There is no reason to believe that identical twins are hereditary since the conception of identical twins does not depend on hormones or genes passed down.
Some families do have a higher number of identical twins than others, but there are no genes that can be linked to explain it.
Chances of Having Identical Twins
The chance of having identical twins is not dependent on any type of hereditary gene. Everyone has the same chance of conceiving identical twins, which is 1 in 250.
These chances do not increase or decrease based on age, weight, height, race, or ethnicity.
Do Identical Twins Have a Higher Chance of Having Twins?
An identical twin does not have a higher chance of having twins than anyone else. The odds are still the same: 1 in 250. This is because hormones and genetics do not come into play with identical twin conception.
Do Twins Skip a Generation?
It is a common misconception that twins skip a generation. The chances of having fraternal twins depend on genes, weight, age, and even height, but there is no evidence that any of these will change from generation to generation.
Having identical twins is simply a random occurrence when the fertilized egg decides to split.
Chances of Having Twins After 35
The chance of having twins does increase with age. A woman between the ages of 35-37 has the highest chance (almost 7 percent) of conceiving twins.
The increase in chances comes from the increase in the production of the follicle-stimulating hormone, which could lead to the release of more than one egg.
What Factors Make You More Likely To Have Twins?
There are several factors that increase your chances of having twins that you may not be aware of. As we discussed earlier, genetics and age can increase your chances of having fraternal twins.
However, some other things can factor into increased chances of having twins.
One is weight; increased weight can lead to increased production of estrogen, and increased production of estrogen could lead to overstimulation of the ovaries, leading to more than one egg being released.
Another factor could be diet. Even though it is not entirely understood or proven, some studies have shown that those who consume a lot of dairy have an increased chance of having twins.
This may be due to the growth hormone given to cows leading to an increased hormone level in women, resulting in more than one egg being released.
Are Twins Hereditary Through the Father?
The father’s genetics does not seem to play into the chances of conceiving twins. The chance of conceiving twins is based solely on the mother’s genetics and hormones.
Why Does Breastfeeding Increase the Chance of Twins?
Women who are breastfeeding are at an increased chance of conceiving twins. This seems to be due to breastfeeding increasing your luteinizing hormone and prolactin.
LH has an effect on ovulation, and increased levels of prolactin can increase the amount of the follicle-stimulating hormone, resulting in the increased chance of releasing more than one egg during ovulation.
What Country Has the Most Twins?
Africa holds the record for the number of twins born. Most of the twins born there are fraternal twins, meaning they came from two separate eggs.
It is believed that differences between African women’s genetics and diet versus women in other parts of the world play a big part in this.
Closing Thoughts
It is easy to look at a person’s hair, eye color, body shape, and other physical factors to see that it was clearly genetics passed down by the mother or father, but not many people think too much about what is going on inside a person’s body being passed on by genetics.
For a female, genetics from her mother will play a role in determining her own pregnancy, including the chance of having fraternal twins.
Conceiving identical twins is just something that can not be explained other than the luck of the egg splitting, making two babies with identical DNA.
Mom of three (including identical twin boys), wife, and owner of Parents Wonder. This is my place to share my journey as a mother and the helpful insights I learn along the way.