From Romulus and Remus—the parable of the twin brothers who based town of Rome—to the synchronized speech of Australia’s “Twinnies” Paula and Brigette Powers, equivalent siblings have lengthy impressed our fascination and creativeness.
In school, these of us who aren’t twins have been usually envious of siblings so alike they may swap round, tricking their lecturers or mother and father.
At Twins Analysis Australia, we work with 75,000 twins to grasp extra about each their similarities and their variations, and the way that pertains to human well being.
Not too long ago, my colleague Professor Sarah Wilson and I contributed to the TV Present “Australia’s Most An identical,” the place 100 units of twins take checks and challenges to attempt to win the crown of the nation’s most equivalent pair.
So, what is the science of equivalent twins? How do they type? How alike are they actually? And what can they inform us about genetics, the surroundings and human improvement?
How equivalent twins are shaped
An identical twins, also called monozygotic twins, type when a single fertilized egg, referred to as a zygote, splits into two embryos.
This normally occurs within the first two weeks after conception and the timing of the break up influences whether or not the twins share a placenta or an amniotic sac.
Earlier splits end in extra impartial improvement. Later ones can result in shared constructions—or, in uncommon circumstances, conjoined twins.
For a few years, scientists believed this was a easy ‘fission’ or division course of. However newer theories counsel the image is extra complicated.
Some researchers suggest that two cell clusters could develop independently inside one embryo, quite than splitting.
However the actual mechanism continues to be unclear.
Twin synchrony and ‘twintuition’
An identical grownup twins, like Paula and Bridgette Powers, who’ve spent virtually each second of their lives collectively, usually report a way of “twintuition“—an intuitive consciousness of what their twin is pondering, feeling, or doing.
Generally, this even leads to them talking in good synchrony.
It is easy to see why folks consult with this as “twin telepathy.”
However it turns into tougher to elucidate when twins who aren’t in the identical room say they will really feel and even see what their twin is experiencing.
Once we examined this capacity in “Australia’s Most An identical,” we noticed fascinating outcomes—however you possibly can determine for your self whether or not this phenomenon may truly be actual.
How genetically equivalent are equivalent twins?
An identical twins are sometimes mentioned to share 100% of their DNA. Whereas that is principally true, fashionable genetic know-how tells a extra detailed story.
After the embryo splits, tiny adjustments—referred to as post-zygotic mutations—can happen in a single twin, however not the opposite.
These adjustments are normally innocent, however they imply that no two equivalent twins are fully equivalent on the DNA degree.
These genetic variations are delicate—only a few letters out of three billion. However they will affect traits or well being dangers, particularly in the event that they have an effect on genes that regulate improvement or immune responses.
This helps clarify why one twin may develop a situation like most cancers or autism whereas the opposite doesn’t.
How epigenetics contribute to the variations between equivalent twins
Epigenetics refers back to the chemical tags that sit on our DNA and assist management which genes are turned on or off.
These tags do not change the DNA itself, however they do have an effect on how our cells learn it. Epigenetic patterns are influenced by issues like food plan, stress, air pollution and maternal well being throughout being pregnant.
At start, equivalent twins have virtually equivalent epigenetic profiles. However over time, variations emerge.
One twin could train extra, eat otherwise or expertise completely different stressors.
These experiences change their epigenetics, which in flip impacts how genes are expressed. Through the years, these adjustments can result in variations in persona, well being or how every twin responds to drugs.
Different components create variations between equivalent twins
Even earlier than start, twins can have very completely different developmental experiences. For instance, the place every embryo implants within the uterus impacts how a lot blood circulate and vitamin it receives, which might affect their start weight and progress.
This is named developmental variation. It is a key motive why genetically equivalent twins can find yourself so completely different.
Genes are like a recipe, however the surroundings and random probability can affect how that recipe seems.
Because the neuroscientist Kevin Mitchell mentioned, “you possibly can’t bake the identical cake twice.”
Are twins actually hereditary?
There is a widespread perception that equivalent twins run in households—however that is not true.
Fraternal (dizygotic) twins, who come from two separate eggs, could be hereditary, particularly if the mom tends to launch a couple of egg at a time.
An identical twins normally happen randomly. They seem at a relentless price world wide—about three to 4 per 1000 births—no matter ethnicity or household historical past.
There’s some proof that assisted reproductive applied sciences (like IVF) could barely improve the probabilities of equivalent twinning.
Twins can have completely different well being circumstances
An identical twins do not all the time share the identical well being outcomes. One may develop bronchial asthma, diabetes or melancholy—whereas the opposite stays wholesome.
These variations can come up from epigenetics, from distinctive life experiences or from variations in how the twins developed within the womb.
For example, if one twin acquired extra vitamins throughout being pregnant, that may have an effect on their lifelong danger of coronary heart illness or weight problems.
Infections, drugs and trauma can even have an effect on one twin however not the opposite. These variations present us how vital surroundings and timing are in shaping well being.
How twins assist analysis
Twin research are a robust option to perceive what shapes human biology. By evaluating equivalent and fraternal twins, researchers can estimate how a lot of a trait comes from genetics and the way a lot from the surroundings.
Research of equivalent twins, specifically, enable researchers to deduce trigger and impact.
Twins Analysis Australia, primarily based on the College of Melbourne, has been conducting these research for over 40 years. Its work has revealed genetic hyperlinks to breast most cancers and epilepsy and proven how life-style impacts mind growing older.
It has additionally helped us perceive how genetics influences studying, reminiscence, and psychological well being.
With over 35,000 twin pairs in its database, Twins Analysis Australia helps to reply a few of life’s largest questions—about well being, persona and the way we develop into who we’re.
So, simply how equivalent are equivalent twins?
The reply is: not as equivalent as you may assume.
From tiny genetic adjustments to the random occasions of improvement, equivalent twins are each alike and distinct.
It is exactly these small variations—and highly effective similarities—that make twin research such a beneficial window into what shapes us all. And that is precisely what equivalent twins themselves inform us: they’re true people.
Quotation:
Simply how equivalent are equivalent twins? (2025, June 25)
retrieved 25 June 2025
from https://medicalxpress.com/information/2025-06-identical-twins.html
This doc is topic to copyright. Other than any honest dealing for the aim of personal examine or analysis, no
half could also be reproduced with out the written permission. The content material is supplied for data functions solely.
