Twins!! Well, that’s even more exciting.
There are two types of twins. Identical and non-identical twins.
In non-identical twins, the mom released two different egg cells, one in each tube.
In this case, two sperm cells would fertilize them and produce two zygotes.
Because they are from two different eggs, they tend to have clear differences among
them when they are born. The scientific name for this kind of twins is dizygotic. Non-identical twins are also called fraternal twins.
In identical twins, there is only one egg cell from the mum and one sperm cell from
the dad. Hours after fertilization, the zygote splits into two new zygotes. This means
they will grow into two very similar foetus and identical babies. The scientific name
for this kind of twins is monozygotic. This kind does not happen often. In fact, identical
twins make about 1/3 of all twins.