Twins are two babies born on the same day to the same mother. All twins are siblings – brothers or sisters – so they will always have some similarities in their appearance. However, only some sets of twins are identical.
Identical twins form from a single fertilised egg. After fertilisation, this splits into two and an embryo forms from each of the two cells formed. Every thing about the babies is therefore identical – they have the same genes and the same patterns of gene expression; they are like two clones of the same person.
Twins that are non-identical are produced from two separate eggs that are fertilised by two separate sperm. Both implant and grow in the uterus at the same time, but they are like an ordinary brother or sister; they are not genetically identical.
Whatever type the twins are, they are still completely individual separate people and their environment and experiences can shape them to be completely different, even if they look the same.
Identical twins form from a single fertilised egg. After fertilisation, this splits into two and an embryo forms from each of the two cells formed. Every thing about the babies is therefore identical – they have the same genes and the same patterns of gene expression; they are like two clones of the same person.
Twins that are non-identical are produced from two separate eggs that are fertilised by two separate sperm. Both implant and grow in the uterus at the same time, but they are like an ordinary brother or sister; they are not genetically identical.
Whatever type the twins are, they are still completely individual separate people and their environment and experiences can shape them to be completely different, even if they look the same.