Why are there identical twins, some are not?

Not all twins are identical, like each other's "photocopy". There are twins not the same, they can share the same birthday, but the genetic similarity is only equivalent to other siblings. Why did this strange thing happen?

This comes from the mother's pregnancy mechanism. What happens in the first days of pregnancy can determine whether the twins are identical or not.

Why are there identical twins, some are not? Picture 1

The process of conception of a woman

Most women produce only one egg a month, but a man can produce tens of millions or even 1.2 billion sperm in each sex.

When having sex without using contraception, one of them is likely to fertilize an egg. At that time, the woman will be pregnant. Then the fertilized egg will undergo a long development process to become a single baby. The fertilized egg is called a zygote.

In the case, the egg is not fertilized, the woman will have her period and next month, a new egg will be produced again.

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The case of identical twins

Human genes are unlike anyone else and are compared to the "scrolls" for our bodies to grow. This helps each person have a unique appearance.

Each person's genetic scroll was halfway from mother and half from father. Therefore, every person is born with the characteristics of both parents and never the same.

The same case happens only if two people are brothers or sisters with identical eggs. Normally, when a father's sperm fertilizes with an egg of the mother only gives birth to a zygote and only develops into a single fetus. But during the first few days of conception, something happened that this zygote developed into two identical embryos and carried identical genes.

Then, the two embryos will develop in parallel into two children, they have a genetic photocopy of "photocopy" of each other, in this case known as single zygotes twins. This is the reason why the twins are identical from hair color, eye color . and of course the whole sex because there will be no case of twins of the same sex.

Why are there identical twins, some are not? Picture 2

The case of twins is not the same

Most women produce only one egg per month. However, there are special cases because sometimes, a woman can produce more than one egg in a month.

In that case, if both eggs were fertilized by two different sperm, in the mother's womb in the beginning there were two different zygotes, not one. This is called a twin zygote twin.

The same twins have a genetic similarity to just two normal siblings, not the same gene as the identical twins.

Identical twins may be of the same or different sex.