Scientists describe twins as two beings who share the same uterus at the same time.
They are further distinguished based on whether they developed from one or many eggs, and whether they shared a placenta.
The normal conception period for twins is 38 weeks. This is attributed to the increased demands on the mother’s body and inability of the fetuses to receive all the needed nutrients.
Identical twins form when one fertilised egg splits and develops into two babies who have the same genetic information.
They are also characterised by having separate placentas.
Statistics from the BetterHealth Channel show that around one in three sets of twins is identical. This is attributed to the fertilised egg dividing yet it contains a tiny collection of cells.
Notably, splitting happens later in a small number of identical twins with both twins sharing an inner sac, known as the amnion, and a placenta.
In most cases, they are described as monoamniotic twins, or MoMo twins.
Identical twins are mostly of the same sex. Reports show that despite identical twins sharing similar genes, they do not always look the same.
This is because their lives are not only shaped by their health and general development but also by experiences in the womb and after birth.
Mirror images
Reports also show that approximately one-quarter of all identical twins tend to be mirror images of each other. This is where the right side of one child matches with the left side of the other child.
Furthermore, they have similar genetic makeup where they share about 85 per cent of their DNA.
Fraternal twins, on the other hand, are formed when a woman's ovaries releases two eggs and two separate sperms fertilise each egg. This leads to two genetically unique children.
During pregnancy, the developing babies get oxygen and food from their mother through separate placentas and umbilical cords.
These twins are mostly deemed to be different from siblings who were born on separate dates. T
They are also bound to share many similarities such as physical characteristics like complexion.
Reports by Australian Health show that around two in three sets of twins are fraternal.
There is a 50-50 probability that the twins may be of the same or the opposite sex. In most cases, the twins are bound to have different hair and eye colour.
Rarely do these twins share a placenta. If they do, which is a rare occurrence, they are called chimeric twins.
Some of the factors attributed to a woman having twins includes having a history of twins in the family.
Other factors are being over 35 years, a history of having given birth to several babies, and taking fertility drugs.
