Do Identical Twins Have the Same Gender? (All Possible Answers)

Identical twins always have the same gender. The zygotes of identical twins are created when the same sperm fertilize a single egg. 

That single egg is called a progenitor cell. This cell somehow gets split into two different cells. So they have the same gene. That’s why they have the same gender.

It is not possible to have a different gender for identical twins. When there are different genders, understand that they are not identical – either semi-identical or non-identical.

Why do identical twins have to the same gender or not?

identical twins have to the same gender or not
identical twins have to the same gender or not?

Due to bathing issues, identical twins are more likely to be female. These issues can be lower birth weight and breathing problems in the newborn. The average weight of a male baby is greater than that of a female baby. 

That’s why containing two male babies is slightly harder for a mother than containing two female babies. Some Israeli researchers researched 2700 twin babies and found more female twins (16%) than male twins (14%). (Obstetrics & Gynecology)

According to the head of the research team, Dr. Marek Glezerman of Tel Aviv University, the risk of giving birth to a male twin is higher than that of a female twin. The lack of testosterone hormone is one of the main reasons. 

That’s why more non-twin males are born. According to the Twinregisty organization, male twins tend to die more than female twins in the womb. As a result, identical twins are more likely to be female than male.

What causes identical twins?

No clear scientific explanation is available to explain the reasons for identical twins. However, a study says that only a single zygote births identical twins. That’s why an identical twin is also called a monocytic twin. 

For an unknown reason, the embryo collapses in the mother’s womb. As a result, her progenitor cells get split into two different cells. Two cells become two different fetuses with the same gene. That’s why the gender of identical twins is always the same. 

However, no scientific reason for how the progenitor cells split has been found. Some theories say the reasons are

  • An unknown enzyme is located in the sperm.
  • When more time is required for the egg after ovulation in the mother’s body
  • A different type of mutation changes the blastocyst cells.

Can identical twins look different?

Undoubtedly, identical twins can have different looks. They may look different even though they were created from the same sperm or zygote. Identical twins may not always look alike, so brothers or sisters can seem distinct from one another due to certain environmental circumstances. 

These environmental factors include the various illnesses they affect, radiation, generation defects, and the amount of nutrition they receive while in their mother’s womb. As a result, they have unique looks. 

These distinct looks and behaviours are also a result of these diverse lives. Therefore, twins do not necessarily appear alike. They may have different behaviours and different appearances.

Do identical twins have the same fingerprints?

Every person is unique because of his or her fingerprint. Fingerprints also make identical twins unique. Identical twins have the same DNA sequence and appearance. Their fingerprints may appear similar but have minor differences. 

There must be a slight difference between the DNA of identical twins. So, in that sense, fingerprints are unique to each person. Different factors change their fingerprints at the time of development in the womb. 

Some environmental factors, like disease and mutation, are responsible for these differences. Also, genetic factors are related to these changes in fingerprints between identical twins. Fingerprints are a surefire way to tell apart identical twins.

Do identical twins have the same DNA? 

Identical twins share the same genes from their parents’ bodies. But, their DNA isn’t the same. Because of mutation, these differences occur. The difference doesn’t need to be in a close period when their bodies are forming in their mother’s womb. 

A research team says there are some factors when the DNA of two twin babies changes. These factors can occur because of environmental influences, defects in a distant generation, or radiation. Some diseases, like cancer, can also change their DNA after birth. 

This research team researched 381 identical twins and found only 10% had the same DNA. The other has different DNA, which was transformed long before their birth. That’s why when two identical girls marry two identical boys and give birth to two children; those children don’t look the same.

Do Identical twin have the same behavior? 

No, they don’t have the same behavior because their personalities aren’t the same. An identical twin possesses the same 46 genes. But when they grow up, various events change their mindset, and they start thinking differently. 

Eric Turkheimer, from the University of Virginia says that their personalities can even become opposites. The treatment they get from different people on different occasions starts to change their behavior.

He also says that in a girl twin, one becomes an extrovert while the other becomes an introvert. A research team from the Center of Regenerative Therapies studied 40 mice to discover twin natural behavior.

They found that some mice like exploring, but some don’t get interested in it. They say the behavior change occurs because of their new brain cells. These cells aren’t the same.


Identical twins are extremely rare in the general birth system. Only 1 identical birth occurs out of 250 births. So many people can have different doubts and opinions about them. One of the doubts is, “do identical twins have to of the same gender?”

They have the same gender because they possess the same gene. These genes are created by only one egg and sperm. But that doesn’t mean they have the same behavior. Their behavior changes when some parts of their DNA change. 

Sometimes they may look slightly different because of some natural factor. Scientists are still finding the details of those factors that create identical tare wins.

Sarah, a health writer and editor since 2014, is an adoring wife and dedicated mother to 2 daughters and 1 son. As the creator of Babies Plannet, she combines her extensive expertise with her maternal dedication to provide essential care and safety advice for infants, nurturing their well-being and happiness. Her writing explores topics like fitness, pregnancy, and women's healthy lifestyles.

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