The odds of twins depends on your age and whether they are identical
twins or not and which ethnicity you have or whether you took fertility
There are two different kind of twins:
- Dizygotic or fraternal or non-identical twins
(2 separate eggs and sperms)
- Monozygotic or maternal or identical twins
(1 egg and sperm which split after fertilization)
Monozygotic twins are also known as identical twins. The incidence of monozygotic twins is the same all over the world, it's 1 in 250 pregnancies. And not matter if you were a monozygotic twin or not, the incidence is still the same.
The incidence of dizygotic twins in general is 1 in 85 pregnancies, but it also depends on your ethnic background. People from Africa have a higher incidence and Asians have a somewhat lower incidence.
If you yourself were a dizygotic twin then your chance having another set of dixzygotic twins depends mainly on your ethnicity and then it's likely a little higher. For the average person it would increase probably from 1 in 85 to 1 in 50 pregnancies.
If you were an identical twins or you previously had identical twins then the risk is still the same, it's 1 in 250.