Identical Twins: How can you tell them apart?
This is the second most common question I encounter as I go through life as a mom of identical twins. And in case of telling identical twins apart, mommy really knows best. Ask my husband. Ask Grandma.
I guess it helped that F was much smaller than his bro R at birth. By the time he caught up, I?ve gotten the knack of telling who?s who. For some parents, it isn?t that easy. I remember stories of parents who had to go back to the hospital to have their babies` identities rechecked.
Which brings us back to the question: How can one tell identical twins apart?
Well, they do have identical genetic make up (except in very rare cases of chromosomal aberration*) so that they are identical physically as well. But they differ in the following:
- Fingerprints, footprints, and palm lines. Interestingly enough, these markings on the body seemed to be determined by something other than genes. This also brings up the fact that when it comes to forensics, physical fingerprints are still more reliable than DNA fingerprints!
- Susceptibility/resistance to certain diseases. Despite identical genetic make up, identical twins can still differ in physiology and how their bodies react to certain diseases. My son F is quite susceptible to respiratory tract infections. He also had eczema as a baby and contracted chicken pox despite inoculations. My son R, on the other hand, is quite robust but had blocked tear ducts as a toddler. They say that identical twins have about 60% health-related resemblance due to differences in gene expression.
- Mirror twins. About 25% of identical twins are ?mirror? twins. Thy have similar but opposite physical characteristics. One may left-handed and the other right-handed. The hair whorls may go in opposite directions. This has something to do with the division of embryo into 2 separate embryos.
Mind you, these are the scientific ways of telling them apart. Now, for more practical tips from an experienced mother of twins, identical twins will differ in the following easily observable features:
- Belly buttons. Even the best doctor on earth can never ensure that he cuts the umbilical cord in exactly the same way to produce identical belly buttons.
- Hair and hair whorls. My boys have the same hair color but one has 1 hair whorl, the other one has 2. The way their hair is distributed around the whorls is also different.
- Birthmarks and moles. As my babies grew older, I noticed differences in skin marks and moles.
- Scars. Despite inoculations, my son F had chicken pox and has a couple of chicken pox scars on his face. Faint scars, but I know where to look at. His brother didn?t get chicken pox and has therefore no pox marks. I`m pretty sure other scars, especially knee scars, will follow.
- Teeth. Although they were teething almost at the same time, my boys` baby teeth aren?t identical at all. R has one incisor tip broken off during a fall.
As the kids grow older, you, as a mom can differentiate them more and more ? from their voices, from the way the smile or turn their head, from their personalities. By the 3rd month, I could tell who?s awake and crying even though I?m in the next room ? a feat my husband only managed 6 months later.
To sum it all up, one mom once told a pediatrician who labeled her babies as monozygotic or identical ?My twins aren?t identical at all. I can easily tell them apart!?
*see Anna`s comment in this post.(18 Jan 2008).