Twins

• The idea of having twins tends to polarise people. Some couples say they’d love the chance to parent two babies and others react in an entirely different way.

• Many reproductive experts believe that as humans we probably have more twin pregnancies than any of us are aware of.

Not identical twins are “dizygotic,” meaning that they developed from two different eggs fertilized by two different sperm cells, while identical twins are “monozygotic”

There are also, in very, very rare cases, conjoined or 'Siamese' twins. These are babies who are joined together and may share some parts of their bodies. Their heads may be joined together, or a different body part is joined.These twins come from the same egg but it hasn't divided properly. They are always the same sex.

Twinning occurs one of two ways: either a woman releases two eggs instead of the usual one or she produces only one egg that divides after fertilization. If she releases two eggs, which are fertilized by separate sperm, she has fraternal twins. When a single, fertilized egg divides and separates, she has identical or paternal twins.

JAVIER BARAJA

PAULA BUNGARD

MANUEL ARIAS

BY