Yesterday, they celebrated their birthday with family and other residents at the hospital wing of Mossbrae Healthcare, Mosgiel.
Born in Riverton in 1915, Frank said he weighed two pounds (900g), and Cecil just a pound and a-half (680g) at birth.
"The doctor said `Put them in a dark room, you'll never hear them'," Frank said.
The twins have outlived their six siblings, having lost sister Maisie, who was also at Mossbrae Healthcare, just a couple of weeks ago, aged 91.
Twice widowed, Frank moved into residential care this year.
The less frail of the pair, he put his long life down to staying fit and not "sitting around".
Growing up, the twins had little, as their father's job with the railways was poorly paid and he had eight children to raise.
They had an active childhood, fishing and hunting rabbits.
The teachers at school put ribbons on the boys' coats to tell them apart.
Frank wanted to be a carpenter, but could not get an apprenticeship, and both followed their father into the railways.
A life-defining event for Frank was being one of the first on the scene of the Tangiwai railway disaster on Christmas Eve 1953.
Stationed in Ohakune at the time, he would "never forget" the devastation that night.
He helped passengers of the disaster in which 151 of the train's 285 passengers died.
Cecil's daughter, Daphne Harkness, said it was a privilege to still have her father and uncle at the grand age of 95.
Cecil was widowed about two years ago. He had three children, six grandchildren, and seven great-grandchildren.
Frank had two children, four grandchildren, and six great-grandchildren.
Activities co-ordinator at Mossbrae Healthcare Heather Martin said the pair were "just delights".
