As soon as the phrase “identical twins” is mentioned we immediately look for ways of telling them apart and ways in which they are different because we assume they are exactly the same.

Interestingly enough, one of the more common physical differences is with their teeth, even as babies.

Many dental issues are influenced by environmental factors and not genetic factors and is one of the reasons that identical twins can be different in appearance, personality and character.

As a family, we are part of a medical research programme and there have been questions in relation to their teeth.  Did they cut their first teeth at the same time? Did they get the same pattern of teeth at the same time?  In response, I can tell you that my identical twin girls did not get their teeth at exactly the same time and even now at age 2 their teeth are different and are a way of telling them apart if you don’t know them very well.

One twin has very straight and evenly spaced teeth and the other has teeth that are on a slant so to speak.

Another difference we have with our identical twin girls is with their weight.  There has always been a difference since the womb and the difference remains now at age 2.  The explanation for this physical difference is that whilst identical twins form with the same set of genes its not simply the genes that dictate their development.  The environment has a big impact also.  If may be that one twin had a more advantageous connection to the placenta receiving the first run of nutrients resulting in the difference in size and physical difference.  I think this factor in our case could possibly be the reason why one twin has much finer hair than the other twin.

Epigenetic Differences

There is another study and explanation offered by scientists for the differences between identical twins. I will not begin to try and explain it myself but you can you can read it by following the link below.

http://www.nytimes.com/2005/07/05/health/05gene.html

Twin Research

There are many research studies of identical twins because of their genetic makeup and one which I recently read about was the study of aging.  As twins are genetically programmed to age the same way the study was able to show how environmental and lifestyle factors influence the way we age.  This particular study used still photographs of each set of twins and asked an independent panel to rate the differences in the appearance of each twin and whether or not one twin looked older than the other.  All of the typical factors such as smoking and exposure to the sun increased the appearance of ageing.  They even said that divorced twins appeared to look on average at least two years older than a twin who was married or widowed!

I will keep adding interesting facts and reading material to the blog in relation to this fascinating subject!