How Do people have twins?

1)Identical twins (monozygotic):

Identical twins occur when a single fertilized egg (zygote) splits into two separate embryos. This can happen within the first few days after fertilization. The resulting twins share the same genetic material and are always the same sex. Identical twins account for about 15% of all twins.

2) Fraternal twins (dizygotic):

Fraternal twins occur when two separate eggs are fertilized by two different sperm. The resulting twins are genetically distinct and can be of the same or different sexes. Fraternal twins account for about 85% of all twins.

Factors that increase the chance of having twins

- Genetics: Some women have a higher chance of having twins if their mothers or sisters are also twins.

- Age: Women who are over the age of 35 are more likely to have twins.

- Race: African-American women are more likely to have twins than women of other races.

- Assisted reproductive technologies: Women who undergo fertility treatments, such as IVF, are more likely to have twins.