A recent study found that nearly a third of twins were incorrect when asked to identify if they were identical or not. Why does it matter and how can you find out for sure?

Mother of two-year-old twins, Kylie Tyrell, discovered the importance of knowing her twins’ genetic identity when one was diagnosed with a rare immune disorder.

Kylie had only recently found out for sure her twins were identical and this led to the other twin, who wasn’t displaying any symptoms, to be tested and the discovery both twins had the disorder.

“I hope that some parents hear my story and realize that if they don’t get their twins tested for their own curiosity, at least get them tested as a medical precaution,” she says.

A joint study by Twins Research Australia and the Murdoch Children’s Research Institute involved twins who were uncertain of their zygosity (i.e. if identical or not) and undertook a DNA test to find out for sure. It found that nearly one-third of the twin pairs were incorrect when asked to identify their zygosity prior to the test.

“We found a substantial proportion of parents and twins had been misinformed by their own parents or medical professionals,” according to TRA’s Deputy Director, Associate Professor Jeff Craig.

Why is it important?

The study showed that knowing their true genetic identity provided twins with peace of mind. It is also important for:

• Bonding of twins
• An individual’s right to know
• Tissue compatibility in organ transplantation
• Assessing disease risk
• Legal and educational reasons
• Estimating the likelihood of the mother or close relatives giving birth to further sets of twins

Jeff says the confusion often arises due to wrong assumptions that identical twins always share a placenta in the womb, and always look and behave identically. But nearly one-third of identical twins and all same-sex non-identical twins have separate placentas.

How to be certain?

He says the only way to know for sure whether same-sex twins are identical or fraternal is to have a DNA (zygosity) test done.

It is an easy process with a DNA cheek-swab test kit mailed to you. A special discounted rate of $120 per twin pair is available – find details at TRA’s website here

“I think it is important for twins to know their zygosity for certain. As they say, knowledge is power,” says Dr Craig.

To keep up to date with the latest in twin research, visit Twins Research Australia at www.twins.org.au. You can also connect with us on Facebook, Instagram and Twitter

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