What are Identical Twins?
They’re also known as monozygotic (MZ) twins and are created when a single egg is fertilized and splits into two. Therefore, they share genes and are of the same sex.
During gestation, they receive nourishment from their mother’s blood through the placenta and into their blood vessels in the umbilical cord which serves as a connector between the babies in the womb to their mother. About 70% of these one-egg twins have one chorion and one placenta.
The chorion is the double-layered outermost membrane surrounding the embryo and is essential to the formation of the placenta which is an organ that grows inside the lining of the uterus during pregnancy.
Is Their DNA Identical?
When the egg split during fertilization, they had identical DNA. However, during gestation, they may use their DNA differently thus causing differences in their DNA by the time they’re born.
Many times identical twins look like a mirror image of their birth mate. Even though they share the same DNA code, some have physical differences.
Environmental factors contribute to their differences. Some of these factors include what they eat, their sleep patterns, and the effects of physical activity. One may be taller than the other or weigh more than the other one. Sometimes, one may have a deficiency whereas the other one doesn’t.
The development of their fingerprints happens in the womb. Their activity, access to nutrition, and position inside the womb contributes to the development and differences in the ridges and the branch markings of their fingerprints. Thus, their fingerprints won’t be identical.
You may have heard about how some twins may sense what the other twin is thinking or feeling without prompts from their sibling. This is referred to as “twin telepathy” and makes them “biologically interchangeable.”
The occurrence of this perceived ability may be due to their genetic similarity, the closeness of the two, or a combination of these factors. Most of these reported occurrences are due to personal accounts and aren’t backed by scientific evidence. However, some research studies have shown similar alpha wave patterns.
Brain waves are when a group of neurons communicates via an electrical signal with another group of neurons. The brain produces five of them with alpha waves being in the middle. These alpha waves occur when you’re awake and not focused on anything in particular. You’re in a state of rest.
Do Twins “Run in Families”?
Identical twin births occur in 3 to 4 per 1,000 births worldwide. Most cases don’t involve genetics. However, there are cases of families having higher occurrences of these twin births.
On the other hand, dizygotic (DZ) twins are more likely to run in families. Their occurrence rate is 22.8 per thousand in the world. They’re also known as fraternal twins and occur when a different sperm cell fertilizes two egg cells in the same menstrual cycle. Hyperovulation occurs when more than one egg is released in a single menstrual cycle.
However, there are other factors that may influence the likelihood of having DZ twins such as the mother’s age, height, weight, ethnicity, diet, body composition, previous pregnancies, and the use of assisted reproductive technologies.
It doesn’t matter how identical twins come into existence. There’ll always be a fascination with seeing two individuals who appear identical. It’s like observing a walking reflection of someone.