How Identical Are My Identicals?

Twins are strange. Whether you have fraternals or identicals the similarities, differences and ‘rules’ of DNA are fascinating. Well I find it fascinating anyway! I’ve never looked into DNA so much, I feel like an honorary scientist since the girls were announced! Naively I always assumed that identical twins would be…well…identical! But now that I have some I can see myself the differences that are starting to appear as they get bigger. Here’s a few that I have found out about…


I think it’s a pretty well known fact that everyone has individual fingerprints. Like snowflakes, no two are the same. Even two babies who share the exact same DNA. But do you know why? Although some say it’s not conclusive, most answers are given as the following. Fingerprints are formed in the womb, along with rest of your tiny tot. It’s weird to think that on those teeny weeny fingers there are already prints stamped and etched that will last for their entire lives. Inside the womb, when the babies start to explore and reach out, their still forming finger tips touch the walls of their surroundings. These touches create what is known as ‘friction ridges’ in the flesh and that is what the lines of your fingerprint are. So no two will be the same, even twins who share the same growing space, as no two babies will ever touch in the same places, with the same pressure etc etc. And that’s how ya fingerprints were made people!


In Beau’s left eye she has a petal shaped ‘flaw’ in her iris. It’s not in any way a flaw but I lack another way of describing it. But in Bebe’s left eye there is nothing. Just like fingerprints, no two irises or retinas will ever be the same. Hence the retina recognition, along with fingerprints, now being so widely used as a security feature. This is again, like the fingers, down to environment during development. Things such as blood vessels placement and exposure to light and dark can all have an effect on your eyes features. Whereas colour can be inherited from your families, the details of your eye are all up to what you are exposed to during your growing stage!


If you’ve read our other posts, you will know that Beau has an unfortunate allergy to cow’s milk protein. It’s fairly common with many formulas now being made to tackle the allergy and a lot of babies growing out of it within a year or so. But Bebe hasn’t got an issue with regular milk. So how comes one baby has an allergy when her twin sister doesn’t? In a study on DNA and allergies, only 65% of identical twins had the same allergies (dropping to a low 7% for fraternals). I was shocked to learn only 20% shared asthma, as asthma seems the most common allergy. No single gene was found to be the reason or cause for shared/not shared allergies. Rather it is suspected that outside factors, reacting with the genes, cause allergies to occur. So basically another case of DNA being affected by environment during development.

Most things I looked into were pretty obvious to think of but I was more interested in the why. It all seems to come back to the fact that when the girls were first made they had identical DNA, but with their growing environment being different for each baby (especially since they were grown in separate sacs) this left a slightly different impression on each one. My two even smell slightly different. Very similar baby smell but just slightly different. Hair colour is another as each child is exposed to day light and sun light differently, their hair colour can change and alter and therefore look different to their twin. So really, all in all, they will have the same basic features but what they are exposed to during their lives will ultimately determine how identical they actually are!

If I’ve written something incorrectly or researched something wrong, please give me a shout. I’d love to know, just for the geek in me really 😉


Allergy Link

Fingerprint Link

Eyes Link


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