Patient information from DNA Labs

Twin studies

Identical or fraternal? DNA testing can determine the status of twins.DNA profiles can be used to determine whether twins are monozygotic (identical) or dizygotic (fraternal).

Each parent will pass on one allele (genetic type) to their child and both of these then constitute the DNA profile for this child. If twins are identical, they are likely to have identical DNA profiles. If they are not identical, they are expected to have the same genetic makeup as siblings born at different times, ie. fraternal.