Six-month-old girl Kouki and ten-month-old boy Oudiki were abandoned by their separate mothers soon after they were born.
Since then, they have been hand-reared by zookeepers Donna Honey and Matt Stagg at Howletts Wild Animal Park in Kent.
The western lowland gorillas are now doing so well that they are being primed for a return to the wild in their native Africa.
Miss Honey, 25, said that the secret of mothering her two unlikely charges was to behave as much like a mother gorilla as possible.
"We don't tend to carry them," she said. "We encourage them to grip on to us like they would their mum. We also make gorilla noises to make them feel at home."