There are two major ways in which twinning can result. These two ways give rise to the terms identical and non-identical twins.
Fraternal Twinning
For the non-identical twins, a woman produces two eggs, each fertilized differently by different sperm from the man.
Each of these fertilized eggs then continues to grow into a separate baby.
Since each baby started with a different egg and sperm, they have different DNA.
This type of twinning is regarded as non-identical or fraternal twinning.
They are like every other person; they share the same womb and are born simultaneously.
Identical Twinning
The mother produces only one egg for identical twins, fertilized by only one sperm. Normally, this fertilized egg should continue to grow and form only one baby.
However, for reasons still being researched, the fertilized egg can split into two, and each half of the division grows separately into a baby.
So, the two babies are produced from one egg fertilized by one sperm. The babies produced by this union are known as monozygotic twins or identical twins.
A common question is whether identical twins have the same deoxyribonucleic acid, DNA.
What Is DNA?
Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix, which carries the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms.
The genetic information in our DNA determines everything about humans, including our physical appearance and personality traits.
A Look At Monozygotic Twins
“Monozygotic twins” is the medical term for identical twins. Mono refers to one, while zygote means a cell that’s formed by the fertilization of a human egg by the sperm.
Identical twins are created when a single zygote splits into two. These two entities continue to divide and grow.
This process is technically considered a malfunction of the normal process of development.
The two separate babies formed in this way share the same DNA. However, they aren’t exactly alike.
That’s why every mother can tell her identical twin babies apart; each develops separately and lives a separate life.
Are Identical Twins Completely Identical?
They are not completely identical because DNA is essentially like instructions for building the body; how each person builds that is different.
It explains why identical twins have similar, but not identical, fingerprints.
Many factors play a role in the appearance and behavior of every person, including identical twins.
The environment in which each one is raised can influence a person’s physical appearance and personality.
Furthermore, as twins grow, epigenetic factors create differences between them. The epigenome describes chemical changes within DNA as individual ages.
Hence, identical twins can have different temperament, appearance, and personality.
How to Determine if Twins Are Identical?
The chances of having identical twins are about 3 in 1,000, and about one-third of all twins are monozygotic.
Most twins are fraternal, produced when two separate sperm fertilize two different eggs.
The only way to determine if a pair of twins are identical is to perform a DNA test. DNA testing is carried out on the two people. Collecting DNA samples is quick and painless.
The sample is obtained by swabbing the inside of each twin’s cheek, and then the samples are sent for analysis.
After that, the DNA results from each individual are compared. If they are monozygotic twins, the DNA test results will be 99.99 percent similar.
However, a DNA test result from non-identical twins will generally be about 50 percent to 75 percent similar.
Can Identical Twins Get Away With Crime?
Because identical twins have similar DNA, it may be nearly impossible to distinguish between these individuals when analyzing DNA in crime situations.
However, a more old-fashioned crime investigation model can be used to distinguish between twins.
Fingerprint evidence can help identify the criminal, even if they are identical twins. That’s because even identical twins have unique fingerprints.
So, identical twins may be unable to escape a crime.
Conclusion
Identical twins are formed by splitting a zygote from one egg and sperm. Although they share similar DNA, it is not completely the same.
The only way to identify if a pair is identical twins is to conduct DNA testing on them.
Author Bio:
Guest article by Dr. Charles Davies, a medical doctor at Brookside Medical Practice, a clinic in Lagos that specializes in family medicine and DNA testing.
