Siamese twins. Who are they?

Siamese twins are twins that have the merged parts of the body from their birth. That happens if the zygote of identical twins was not fully divided. The probability of having Siamese twins is one of 200 000 deliveries. More than half of all Siamese twins are born dead. The level of babies' survival is 5-25%. Frequently the Siamese twins are female (more than in 70% of cases).

The most famous Siamese twins were born in Thailand and were two brothers that were giving shows in the circus that travelled all over the world. Twins had the only breast. If they were born nowadays, doctors could separate them.

There are a lot of kinds of Siamese twins that differ in dependence on the part of the body that is merged. Sometimes one of twins stops developing parasitizing on the other twin.

In English there is a term to call such twins that is "conjoined". But is fact this term is very contradicting as it means that somebody joined these two twins while they are born already being joined. That is why it is better to use the international term "Siamese twins".