Are Twins Rarer than Redheads?

Give me a piece of Dynomite Pie* and I might tell you!

Okay, Okay! The short answer is yes! We’re a lot less common than your average red head.  Redheads (and those with intersexual traits, by the way) represent 1.7% of the world’s population, while monozygotic twins – identical, that is  – occur at a rate of about 3 in every 1000 deliveries worldwide, or 0.2% of the world’s population.  There are about 10 million identical twins in the world, while there are nine times as many redheads and individuals of intersexual traits.  But people with red hair and blue eyes the rarest minority in the world, with only 1% having both. So, each one is about as rare as a four-leaf clover.

Oh, by the way, did I mention I’m a twin? Identical? Monozygotic? Rarer than a Weasley?

My laughing sister was born first, arriving in the world four minutes before me, large enough to go home immediately.  I, by contrast, was completely abandoned immediately after coming into the world because I weighed a little more than four pounds when I emerged, blinking helplessly under the harsh lights of the incubator, the warm comfort of my sister’s fist no longer shoved solidly in my mouth like it had been for almost nine months.  

How special has this been in my life? The answer is still miles off on the horizon, like the Green Star Kiswahili speakers told me I travel under in Tanzania, the rarefied sign of special luck that is still miles off, just barely visible on the horizon.  Twinning might be just as rarefied, mythic, and symbolic as the Green Star under which I purportedly walk – or just as nonexistent a force in my existence. 

You may have observed that there are a lot more twins now – lots more than twenty or thirty years ago.  Mothers are waiting longer to have children, and are using fertility drugs and IVG, which increases the likelihood.  My mom had us when she was 32, which was way old back in 1949.

But I’m happy to say that the likelihood of a single fertilization resulting in monozygotic twins hasn’t been affected. It’s uniformly distributed in all populations around the world, in marked contrast to dizygotic or fraternal twinning, which ranges from about six per thousand births in Japan to 15 and more per thousand in some parts of India and up to over 20 in some Central African countries.  Fraternal twinning rates fluctuate by use of in vitro fertilization (there are nearly 21 pairs of twins for every IVF), use of fertility drugs. and mother’s age, accounting for the high twinning rate among Yoruba people.  The tiny country of Benin has an astronomical twinning rate.

But I’m happy to say that my sister and I are as rare as we’ve ever been!

By the way, learning Kiswahili is not as easy as people might tell you, especially in Tanzania, where people speak the purest form of Kiswahili in the world. It’s an agglutinative language, and all your nouns, adjectives and verbs have to agree by class or category, of which there are many.

*Trademark of Inky and Kiwi’s Pie Shop.

Standing on their heads! All Lined Up for Pie!

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