Identical vs Fraternal Twins – Understanding the Differences for Parents

Identical vs fraternal twins: what are the main differences between the two types of twins?

Yes, there are other subtypes of twins. But, in most cases, a woman either gives birth to a fraternal twin or an identical one.

The number of identical twins born is comparatively less, while fraternal twins are more common.

But what sets both of these twins apart? In this article, we have clarified the difference between the two most common types of twins. Keep reading to learn more.

Identical vs Fraternal Twins: The Difference

Having a twin isn’t a choice you get to make. Yes, there are some medical and health considerations you can make to increase your chances of having a twin.

However, it’s not your choice. Not always. We have already talked about how to have twins in another article. You might have also encountered terms such as fraternal twins and identical twins.

So, what are these two different types of twins? Well, for that you have twins are born. This starts with understanding how embryos form. When a woman is ovulating, eggs are released. When the eggs are fertilized by sperm, a new entity is formed, which is called a zygote.

The zygote quickly grows into a small cluster of cells that travel into the fallopian tube and get implanted into the uterus.

It starts to grow and form something called a placenta. The placenta is responsible for providing nutrients to the embryo.

How the eggs get fertilized makes all the difference between an identical and a fraternal twin.

Identical Twin

In this case, the fertilized egg becomes a zygote split into two. These two zygotes are placed into the uterus and contain the same genetic material When dividing into two. The twins born in this process are called identical twins since they share the genetic materials of the same sperm.

Fraternal Twins

In this process, two different eggs are fertilized by sperms from the same donor in the same ovulation cycle. Some people think that only one egg is released in one ovulation cycle. But that’s not the case most of the time. Some people release more than one egg during an ovulation cycle.

This is what is called superovulation. When two sperm fertilize two eggs, you have fraternal twins.

About Fraternal Twins?

As explained above, fraternal twins result from two different sperm fertilizing two other eggs. Dizygotic twins or fraternal twins require a woman to super ovulate and produce more than one egg during ovulation. Babies born through this process can have the same or different sexes.  Here are all the specific factors that separate fraternal twins from identical twins.

Level of similarities

Fraternal twins are identical in terms of the genetic similarities’ siblings share. This is an instance of childbirth of two children at the same time. But they aren’t identical since two different sperms fertilized the zygotes. They don’t share the same genetics since each sperm contains a specific genetic quality.

So, even if someone’s giving birth to twins, one of the babies can have blue eyes and dimples, while the other will only have brown eyes and no dimples. In many cases, fraternal twins don’t get their sexes assigned at birth. One can have children of two different genders or the same gender.

Placenta Development

identical vs fraternal twins: do they share the same placenta? No, for fraternal twins, both zygotes form different placentas when placed in the uterus. The separate placentas nourish each baby separately until their birth.

However, there are chances for both placentas to fuse. This happens when both babies get cramped inside the uterus, and the placenta starts to grow together. These are separate placentas that may look like ones with separate blood vessels.

How Common are Fraternal Twins?

Identical vs fraternal twins: how common is each of them? Identical twins are rarer in nature, whereas fraternal twins are more common. Several researchers say fraternal twins are born higher in numbers than identical twins.

Most fraternal twins are born in Africa and North America. Studies suggest that almost 17 out of 1000 births are fraternal twins in these parts.

Who has the Highest Chance of Giving Birth to Fraternal Twins?

In most cases, people who want to conceive twins take treatments like IVF. Twins born through the assistance of IVF are typically fraternal. In most cases, women aged between 30 to 35 have a higher chance of giving birth to fraternal twins. This is possible because, at this age, they have the highest chance of superovulation. Someone can have fraternal twins under the following conditions.

• They are aged between 30 to 35.
• They have a higher BMI (higher than 30).
• The mother has given birth before.
• Their mother or sisters have given birth to twins as well.

About Identical Twins?

Identical twins are the results of one zygote splitting into two and forming two different babies from the same egg. As explained before, in this case, one egg gets fertilized by one sperm and splits into two before getting placed in the placenta.

Level of Similarities

The same zygote forms two different embryos into two babies with the same genetic qualities. Typically, they share many physical similarities, but that doesn’t mean identical twins don’t have any differences.

How Common are Identical Twins?

Fraternal twins often run in bloodlines. In most cases, someone from the mother’s family has given birth to fraternal twins. But identical twins aren’t related to bloodlines and family trees. Usually, 3 to 5 out of 1000 births are identical twins.

Pregnancy Complications

Here’s another misconception that needs to go away. Many people believe that fraternal twins have two placentas and identical twins have just one placenta. But that doesn’t always happen. So, how do you know if the twins you gave birth to are fraternal or identical twins?

Only a DNA test after delivery can clarify whether the childbirth was due to identical or fraternal twin children.

Antenatal Care for Women Carrying Twins

Antenatal care for women carrying twins happens more frequently than often thought of. The specialist has to constantly monitor or take care of the babies in this case.

Here are some important areas of antenatal care for women who have twins –

• Check-Ups Scans: Compared to single pregnancy, they have more frequent care for the babies. Also, the type of twins one has decides the number of scans required.
• Specialist Care: in most cases, you’ll see an obstetrician or a midwife if it’s a complex pregnancy clinic the pregnant women admitted to.
• Weight Gains: You have to gain more weight than what’s required for someone with one baby. This amount depends on the weight you had before pregnancy and the number of babies you have.
• Hospital Bag: get the hospital bag ready by 2the 6th week.
• Meals: Keep an extra double portion of meals ready by the end of the 26th week.

Zygosity Testing

It’s not easy to tell whether the twins are identical or fraternal during birth. Sometimes, identical twins can be born with different sets of membranes. This can create a misconception that they are fraternal twins.

The only way to tell the difference between identical vs fraternal twins is through a DNA test. This is also called zygosity testing. The identical twins share the same genetic information, while the fraternal twins are different due to two different sperms causing the fertilization. The easiest way to do this is through running a test of the sample of cheek cells or through blood group tests.

You May Like To Read This:

• Ovulation Bloating: Is That A Real Thing?
• Signs Ovulation Is Over: When Does Fertility Window Close?
• Signs Of Ovulation After Giving Birth: Know What Your Body Is Telling You