The only distinguishable differences between the sisters are the tiniest of freckles on Donna's nose and the fact she wears her hair a fraction longer than her twin.
The Irvine-born siblings are among the 14-strong wrestling contingent announced for Team Scotland. They will both compete in the 48kg-weight class at the 2014 Commonwealth Games this summer.
When they tell people they are wrestlers, the petite pair are used to them being confused. "They think it's WWE, MMA or the cage fighting stuff like UFC," says Fiona. "When I explain it I try to make them think about Olympic freestyle wrestling rather than capes and props."
While reluctant to be drawn on who is the stronger of the duo - "If you ask us who is the best it comes down to the day," says Donna - both have their sights on the same goal: a medal in Glasgow.
The sisters, who celebrated their 45th birthdays on Thursday, are used to doing everything together: they are training partners, work in the same sports centre and share a home in Hamilton.
They began their sporting careers at the age of 11 when they took up judo in their hometown of Campbeltown, Kintyre, and went on to compete at the Commonwealth Games in Auckland and Manchester.
Donna was the first to win a medal when she took bronze in 1990; Fiona followed in 2002, also coming third.
The pair turned their hand to wrestling in 2008 to add a new repertoire of moves to their judo technique. After just a few sessions, however, they quickly showed an aptitude and were invited to make the switch as part of a sportscotland institute of sport talent transfer initiative led by Scottish Wrestling.
Their Commonwealth Games wrestling debuts came in Delhi in 2010. By their own admission that was merely a dress rehearsal and they believe Glasgow will be the main performance. "It all felt quite new in 2010 because we'd only been doing it two years but we have six years' experience now," says Fiona.
Beside her, Donna nods. "It feels more like I'm a wrestler now, rather than going through the transition from judo as we were at that time," she says. "We were still making mistakes.
"We certainly both feel far more competitive in world-class events. Before we were a bit like rabbits caught in headlights. We were thrown in at the deep end and had to fight against the best in the world after just a year or two years' wrestling. We are more experienced now."
With no seeding system in wrestling the worst case scenario, they say, would be to meet each other in the first round of the Commonwealth Games as happened in their first international wrestling comp-etition in Madrid. But the sisters remain philosophical.
"If we draw each other, someone is going to lose but at least someone is going to win," says Donna. "We both know what it is like to lose and what it is like to win, so we are always there for each other."
Despite so much time spent in close proximity, they insist they never grow weary of one another's company. "We are never sick of each other," says Donna. "We do fall out but it's just a matter of minutes. We did say that when we went to Madrid, we could have fought in the living room back home and saved a fortune."
Fiona smiles in agreement. "We have never had an argument where it has even lasted hours or days," she says. "It's always just in that moment and then that's it. I know that's probably quite unusual but maybe the fact we do live together, share a mortgage, we have to get on."
The pair, who train six days a week at Emirates Arena in Glasgow, credit their longevity and success in part to that closeness as sisters. "More so in wrestling because we have had to rely on each other for training," says Fiona. "It's not a sport where you can just go out for a run yourself and try to beat a time, you need a training partner to throw about and practise techniques. Having somebody your weight is ideal."
Age, they say, is not a barrier. "In a lot of sports age is an issue for selection but both of us have proven that we can still compete with the younger players and I'm proud we can still do that," says Fiona.
"And that our bodies are willing to put up with the pressure," adds Donna.
They refuse to be drawn on whether Glasgow will prove the last hurrah. "Never say never," says Fiona. "We haven't officially retired from judo either."