Olympic sibling success: Is it all in the genes?
Sibling rivalry can be tough at the best of times, but what if those siblings are competing at the Olympics?
Does having the same genetic make-up mean you are more likely to be in competition?
Or is it training in the same environment which pushes athletes on to succeed?
Here we look at "nature versus nurture" - whether success is about having the same genes or training in the same environment.
Siblings often tease each other about which one is older and going to go grey quicker.
But how does that translate in competitive sport?
The Northern Ireland pair became the first British brothers to win an Olympic medal since Greg and Jonny Searle took bronze in the coxless four at the 1996 Atlanta Olympics.
Richard is 28, weighs 78kg and is 1.78m tall.
In contrast, Peter is six years younger, lighter at 73kg and is taller at 1.87m.
One theory suggests that the age gap could give Peter the advantage as an athlete.
"Genetically and environmentally speaking they will be fairly similar and have access to similar training programmes," said Dr David Fletcher, director of the sport psychology support service at Loughborough University.
"They will progress at a similar rate and keep pushing each other on. With a six-year age gap [such as the Chambers brothers], the older sibling is more of a role model.
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"They have a training partner they are always learning from. Not just physically, but also learning how to handle the sport, the politics and culture."
Genetically speaking, Dr Tim Spector, Professor of genetic epidemiology at King's College London, said age is not a major factor in success.
"It depends on the sport. With some you get better with age," he said.
But there is a continuing debate around whether success is down to genes or training, he added.
"Some believe you can take anybody and train them from an early age to make them an athlete if they have the basic anatomy.
"But if you have an older brother training in an elite environment then the younger sibling may also have the chance to train in that environment."
For Professor Spector it harks back to the nature versus nurture argument.
"It isn't clear cut because we used to think of exercise and training as a pure environmental thing.
"But if you exercise more then you can change your genes.
"If you exercise for more than three hours per week, you can switch off some of the genes which make you put on fat. If you've inherited some fat genes then you can counteract that."
The one that didn't win
Judy Murray is well known for cheering on tennis ace Andy Murray, but she also has another reason to shout.
For Jamie Murray is also a player and competed with his brother in the Olympic men's doubles competition.
They crashed out in the first-round, losing out to Austria's Jurgen Melzer and Alexander Peya.
"We had enough chances to win the matches and both teams played well," Andy told the BBC.
"Doubles can come down to a couple of shots and a couple of points and they got it in the end."
Andy then went on to win a men's singles gold medal by beating Roger Federer and a silver in the mixed doubles with Laura Robson, but for Jamie Murray the match with his brother ended his involvement in the Games.
"It's disappointing," he told the BBC.
And when asked if he was going to stay in the Athletes Village he said: "I don't really want to hang around. There is nothing for me to do.
"You'd just remind yourself that you didn't do as well as you would have wanted, but that's life."
So when one sibling bows out, it might be a safe presumption that there would be elements of jealousy.
Apparently not once athletes get to an Olympic level, according to Dr Fletcher.
"It depends on the individuals and the chances are that if they have gone that far within the sport then it's not a big issue," he explained.
"We see it a lot when one sibling outstrips the other and the other sibling just gives up after that.
"Once you're an Olympian, then I don't think there would be significant jealousy there.
"I don't think Jamie has a great thing to prove, he's won the doubles at Wimbledon and is successful in his own right."
The identical twins
What happens when you get two athletes, with the same genes - identical twins.
They are the same height at 1.8m and both weigh 67kg. Kevin came in fifth at 44.81 and Jonathan sixth at 44.83.
"There are less twins competing in the Olympics than you might imagine," said Professor Spector.
"One in 80 people in the UK are twins and so we ought to have more. There are one in 250 who are identical.
"The Borlee brothers came within 0.2 seconds and you can't get much closer than that.
"But how can someone say that's totally genetic? They do everything together. You know they've had the same environment and training and that's also a factor."
Professor Spector said the genes which lead to success include those in the muscles but that the key gene is probably in the brain.
"It's the willingness to train and do nothing else, and that comes down to the willpower," he added.
"We did some studies in twins around participation in regular sport and it showed that it is down to about 70% genetics - something inside decides whether we get a kick out of it."
Jonathan Borlee has told the BBC how his brother pushes him to improve his performance.
He also explained how it was his sister Olivia who inspired him to take up running after he saw her perform.
Olivia was part of Belgium's silver medal-winning 4x100m relay team at the Beijing Olympics in 2008.
It seems that success runs in the family.
Apparently: "Sibling rivalry is the key to the success of the Brownlee brothers".
And they channelled their sibling rivalry to get to their podium position says fellow West Yorkshire athlete Martin Peace, the chairman of Bingley Harriers.
"Being brothers means they're even more competitive with each other than with everybody else," said Mr Peace, who has trained alongside both brothers.
The triathlon involved a 1500m swim in the Serpentine at Hyde Park, followed by a 40km bike ride via Buckingham Palace and Hyde Park Corner, before returning to Hyde Park for a 10km run.
Alistair won gold but could be seen slowing down his pace and turning his head around, perhaps looking for his brother or perhaps just savouring the glory.
Jonny won bronze after serving a 15-second penalty for mounting his bike too early and was then treated for medical fatigue.
They hugged on the finishing line.
On winning his gold, Alistair said: "It feels a bit underwhelming in a way because Jonny has just collapsed, he's not feeling too good. but it's fantastic.
"Two British brothers on the podium, you couldn't ask for anything more," he added.