Three of the sets of twins, they say, had been born two minutes apart and of each pair first-born were Shana Beneke, Danielle Rose and Ella Southey, while Ariana Sutton beat her brother to the punch by eight minutes and Danielle Mason led her sister by nine minutes.
According to the Kiwi Families website, twins and triplets are becoming increasingly common in New Zealand.
Twin births naturally occur in about one in every 100 pregnancies, the website continues, but the rate has increased due to in vitro fertilisation. Triplets and other multiple births, such as quads and quintuplets are "an extremely rare natural occurrence, with triplets only occurring naturally in 1 in 8000 pregnancies".
A rapid search online revealed that twins can be conceived by two different fathers -- common in dogs and cats but extremely rare in humans -- and identical twins may share DNA, but exposure to different areas of the womb during development affects the fingertip ridges and whorls.
Also, twins sometimes develop cryptophasia, a language exclusive to each set of twins that to others is simply babble. Twins are believed to begin interacting in the womb as early as 14 weeks into pregnancy.