Can Twins Be Different Races? Explanation of How It Happens

| Reviewed By Amanda Lundberg, BSN, RN

Some twins may not look alike at all, even though they were conceived and grew together in the same womb.

Can twins be different races? Given the perfect combination of genes and family history, a pair of mixed-race twins could be born to biracial parents or interracial couples. Interestingly, a set of fraternal twins could have been fathered by different men, leading to different skin tones in the babies.

Let’s take a closer look at the ways that this could happen!

How Twins Could Be Different Races – 3 Explanations

The concept of twins is an intriguing phenomenon in itself. Add in twins of different races, and that is an entirely different level of mind-boggling! So, how does it happen?  

1. Fraternal Twins With Parents of Different Races

The number of interracial couples is growing, and it is possible that we could see more twins of different races as well.

It is possible for twins to be two different races if each parent is a different race. One twin could “take after” their mom’s race, while the other twin might take after the father’s race. 

2. Fraternal Twins With Different Fathers

While it is rare, it is possible for fraternal twins to have different fathers. This is called heteropaternal superfecundation.

Because fraternal twins result from hyperovulation (when a woman releases more than one egg during her menstrual cycle), it is possible for a woman to get pregnant by two different men if she has multiple sexual partners within her fertile window. 

Is Heteropaternal Superfecundation Rare?

While it is rare, heteropaternal superfecundation should not be underestimated.

It is difficult to gather true statistics of its occurrence because many mothers choose not to undergo DNA testing, and therefore, there may be plenty of unreported or unknown cases.

The data that is available from paternity lawsuits have shown that roughly 2.4% of fraternal twins have had different fathers. 

3. Fraternal Twins With Biracial Parents

When one or both parents are biracial, there is a large genetic pool that can yield millions of different results in their offspring.

A mixed black/white mother and a mixed black/white father could have one twin that looks white while the other looks black. 

Can Twins Have Different Fathers?

Yes. It is possible for fraternal twins to have different fathers if their mother had intercourse with more than one sexual partner during her fertile window. 

Mixed Race Twins

Fraternal twins share, on average, half of their DNA. Therefore, they have the potential to look completely different, and they often do. The twins may even be different races, depending on the races of the parents. 

Wild, right?!

Let’s say that a set of twins has one black parent and one white parent. Each of the parents carry genes for physical characteristics specific to their race (skin color, eye color, facial features, hair texture, etc.).

When this couple has fraternal twins, one twin could get more of the black parent’s genes while the other twin could get more of the white parent’s genes. This would cause one twin to have darker features while their sibling has lighter features.

Another scenario that could yield mixed-race twins is if one or both of the parents are biracial.

For example, if both parents are mixed Caucasian/African American, they could have one child who has darker features and looks more African American while their other twin could have light skin and look more Caucasian.

This has to happen with the perfect combination of genes at the time of conception.

If two eggs are fertilized by two sperm that each carry different genes for skin color, one twin could end up with two “white” genes (one from the father and one from the mother) and have white skin, while the other twin gets two “black” genes and has black skin. 

Can Identical Twins Be Biracial?

Identical twins cannot be different races as they share the same genetic information. Only dizygotic, or fraternal twins, can be born different races. 

Unusual Twins

Polar Body/Half Identical Twins

“Half identical” twins form when the egg splits prior to being fertilized. These twins share about 75% of their genetic DNA, which is more than fraternal twins but less than identical twins. 

Semi-Identical Twins

These unique twins share all of the same DNA from their mother’s side, but share only half of their father’s genes. Semi-identical twins develop when two sperm fertilize one egg prior to its splitting. 

Boy/Girl Identical Twins

There are a few reported cases of a genetic mutation in some male twins that causes one twin to lose a Y chromosome and develop as a female.

The twins are technically still identical because they derived from the same egg and sperm; however, they are different sexes. 

Mirror Image Twins

Roughly 25% of identical twins are mirror image twins, meaning they develop reverse asymmetric physical features and appear to “mirror” each other.

They could have opposite birthmarks, swirling hair whorls on opposite sides, or dimples. When these twins face each other, they look like exact reflections (as if they were looking in a mirror). 

Superfetation: Twins Conceived Separately

It is very rare, but sometimes an egg can be released while a woman is already pregnant. This results in twins who are conceived at different times!

As opposed to normal fraternal twins, these twins are conceived during two separate menstrual cycles, and the fetuses will show noticeable differences in gestational development. 

Heteropaternal Superfecundation: Twins With Different Fathers

Twins are always born from the same mother, but it is possible for them to have different fathers.

This occurs when a woman hyperovulates and her eggs are fertilized by sperm from two separate incidences with two different sexual partners. 

Twins of Different Races

This can happen when both parents are of mixed race and each twin is conceived from a separate egg fertilized by a separate sperm. Each sperm and egg must carry the genes for the particular skin color (i.e. black/black or white/white)

Conjoined Twins 

Conjoined twins are identical twins who do not fully separate from each other in the womb due to the incomplete division of the fertilized egg. They may share tissue, organs, or limbs. 

Parasitic Twins

These are conjoined twins who develop asymmetrically with a smaller twin depending on the stronger, larger twin.

The smaller “twin” is not capable of developing into a functioning human and depends on the other twin’s blood supply.

This usually prevents the larger twin from being able to function and grow properly out of the womb, hence the term “parasitic.”

One case of parasitic twins was born in Cairo, Egypt. The larger twin had a second head that could blink and smile but was incapable of living independently. Sadly, surgeons had to remove the second head so that the other twin could survive. 

Related Questions:

How Can Twins Have Different Fathers? 

If a woman hyperovulates and has intercourse with multiple partners during her fertile window, it is possible for her to conceive twins with different fathers. 

Why Do Identical Twins Look Different? 

Small genetic mutations can cause identical twins to have slight differences in appearance. 

Conclusion

Don’t be fooled by the stereotype that twins always have to look alike or even similar. Remember that there is more to it than “identical” or “fraternal.”

Genes are complex, unpredictable, and full of surprises! Sometimes, the perfect combination of genes can yield two extremely different wombmates.