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A DNA test for twins costs just £99 for next day results. Same day results can also be made available for an extra £70. Both of these tests can be ordered direct from our website. The price includes a Zygosity Certificate, which shows which DNA markers the twins matched at.

Twin testing is also known as zygosity twin testing. It involves analysing tiny amounts of DNA from inside each sibling’s mouth. The DNA is found in buccal cells so all you need to do is rub a swab on the inside of each twin’s cheek to collect the cells. Full instructions are included in the testing kit.

Back at our laboratory, our scientists examine specific markers present in repeat sections of the DNA samples. These 35 Short Tandem Repeat (STR) loci include the Amelogenin (gender) locus. The DNA seen at each of these STR loci is compared between the tested individuals; identical twins will share the same DNA profile whereas non-identical siblings will have different DNA profiles.

Whether or not twins are identical depends on how the babies were formed. Non-identical twins are the result of separate fertilised eggs. These babies are no more alike than any other brothers or sisters, and may be both male, female, or one of each. They share DNA in common as in the case of siblings from different births. Identical siblings are formed from a single fertilised egg, which went on to split into separate embryos. This means their DNA is exactly the same.

The only way to conclusively determine whether twins are identical or not, is to carry out a DNA twin test. In utero determination may be incorrect as the placentas of non-identical twins may fuse together in the womb giving the appearance of a single placenta making them appear to be identical. Conversely, approximately one-third of identical twins have separate placentas making them appear non-identical.

This DNA test can also be used to test more siblings to establish whether multiple children from the same birth (triplets, quadruplets, etc.) are genetically identical or not. You can add more siblings to the test when ordering online.

An increasing and novel use of a DNA zygosity profile is as a unique gift idea for multiple birth parents and/or their children. For more information on Zygosity twin testing, please contact AlphaBiolabs on 0333 600 1300; email: info@alphabiolabs.com; www.alphabiolabs.co.uk