Are Identical Twins More Special Than Fraternal Twins?

Examining Social Attitudes Towards Twin Type

Are identical twins more special than fraternal twins?
Are identical twins more special than fraternal twins?. mage Source / Photodisc / Getty Images

As a parent of twins, do you ever feel like there is a weird obsession with “what kind” of twins you have? It seems like the first question everyone wants to know about your children is “Are they identical or fraternal?” As soon as you announce a twin pregnancy, it is the first thing that people want to know. It persists, cropping up every time twins are mentioned. And, when the answer is fraternal, there is an imperceptible pause of disappointment, as if only identical twins are worthy of further consideration.

Parents of fraternal twins sometimes report a subtle sense of slight, being made to feel like secondhand citizens in the world of multiples. Identical twins seem to be the focus of all the attention, while fraternal twins are an afterthought. Some have even been told they’re not “really twins” at all, just siblings born at the same time. 

But are identical twins really more special than fraternal twins? Why does this attitude persist? 


Most of the popular stereotypes about twins relate to identical twins. The concept of twins as clones -- two alike individuals as a matched set --is sometimes associated with identical twins. The general expectation is that twins should be identical, similar in appearance and character, with a supernaturally close relationship. Media stereotypes perpetuate this myth of two identical individuals who look alike, dress alike, act alike and think alike.

But  in reality, most twins - fraternal or identical -- don’t live this way. They are individuals, with independent interests and personalities. Even those who look alike aren’t technically identical. 

For those who are educated about twins, and particularly those that are close to them, twin type is understood in a different context.

Twin type is defined by zygosity, which explains how twins form. While it’s true that identical twins tend to be more similar because of their genetic origins, genes aren’t everything. Identical twins can be as alike or as different as they choose to be. And so can fraternal twins.


Perhaps one reason that identical twins seem to attract more attention is because of their rarity. About one in three sets of twins are monozygotic, or identical. So, fraternal or multizygotic twins are twice as prevalent as identical twins. As with many things, that which is rare holds more appeal. There is a mystique associated with identical twins because they are unusual. 


Identical twins are also less understood than fraternal twins. The causes of fraternal twinning can be attributed to many causes -- family history, maternal age, or fertility treatments. But the causes of identical twinning - exactly what causes the zygote to split and develop two embryos - is not fully understood. Science has yet to pinpoint the reasons behind the formation of monozygotic twins. Perhaps this is another factor that contributes to their mystique.

Twin Relationship

Another factor that differentiates fraternal twins and identical twins is that identical twins are always the same gender, while fraternal twins can be a boy and a girl.

(Yes, there are extremely rare exceptions to this claim.) The relationship between same sex twins is understandably different than between boy/girl twins. But it does not follow that only identical twins share a close relationship. A 2011 study by researchers at American University measured closeness in the twin relationship and reported that the scores for fraternal and identical twins were nearly the same, confirming an earlier theory that “the bond between twins is distinctive regardless of whether they share the same DNA,” and explaining that a shared environment has as much to do with the formation of a twin bond as genetics.


While these examples might help explain the extra appeal of identical twins, they don’t support the notion that identical twins are more important or more special than fraternal twins. In talking to twins and families with twins for nearly twenty years, it is clear to me that every set of twins is different. Some share an extremely close relationship. Others fight constantly. Some are very alike. Some are completely opposite. And they can not be characterized according to whether they are fraternal or identical. 

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