And if you don't believe it, their amazing – and very cute – efforts have been caught on video by their proud Vic and Charley and posted on YouTube. The clip has been viewed nearly 100,000 times.
The mum and dad, from Gloucestershire, didn't think their babies had a special talent until they took them to parent and baby swimming classes for the first time.
Charley said: "I thought all babies could do it. It wasn't until we came to swimming lessons and people got so excited about it that we realised just how unusual it was and how clever they were."
Now dad Vic already has his sights on seeing his water babies in the Olympics.
He said: "Now they can swim and seeing that they were born in an Olympic year, 2012, I would love to see them at the 2028 Olympics possibly, when they're 16, doing the open water swim."
See some more amazing water babies here.