DNA testing for Twins
DNA testing can be used to confirm whether two individuals are identical or non-identical twins and may also be used to confirm a potential donor’s suitability for organ or bone marrow donation.
'Identical' (or 'monozygotic') twins develop from one fertilised egg which divides and develops as two separate embryos. As a result, their DNA is exactly the same, meaning that they will be the same sex and likely to resemble one other.
'Non-identical' ('fraternal' or 'dizygotic') twins develop from two separate fertilised eggs. Their DNA is similar, in the same way that all siblings share similar DNA as a result of having the same biological parents. This means that non-identical twins can be different sexes and are less likely to look the same.