It is evident both inside and outside the ring. Minutes after the end of the first round of the qualifying competition, at the Georgia International Horse Park, both of them are anxiously asking questions about their father, who had, perhaps unwisely, decided to sit through the best part of six hours watching the whole event in the searing heat.
"He's having problems with his breathing," Mike explains, shaking his head with annoyance. "I told him not to expose himself to the sun all day, but he wouldn't listen. Never does."
Their story began back on their father's farm. Both brothers were taught how to ride by their mother, using the family's pony that pulled the milk float. Neither has ever felt the need to use a riding coach since, not with their parents around.
Since then they have shared most of the sport's honours, including a team silver medal at the 1984 Los Angeles Olympics. John is a former European champion as well as a two-time world cup champion, while Michael became the youngest ever winner of the Hickstead Derby in 1980 as a 20-year-old, and has won three European championship medals.
Olympics or not, however, John has found the team doctor to check up on his father. Thankfully, all is well, allowing his two sons to sit down together and discuss the day's proceedings.
It started with a walk around the course an hour before competition was to begin. "We tend to seek each other's advice," says John, at 41 five years Michael's senior. "I seek his more than he does with me," Michael chips in. "It's probably the older brother syndrome."
Although John lives in Huddersfield and Michael is found just outside Nottingham they still see each other four or five days every week due to the packed show jumping calendar which takes them around the world.
"We don't bother phoning each other in the morning to see how we are when we're not competing," Mike explains. "But that's only because most days we are together anyway.
"We've always taken the view that if one of us can't win a competition then as long as the other one does we're happy. Of course, it's even better if the Whitakers can get a 1-2."
The particular order of the honours is, however, keenly fought. "We're close brothers before and after competition, but if we're involved in an individual event then we eye each other as rivals," adds John, balding and striking an unmistakable physical likeness to his brother.
But what happens if he beats Michael into second place? "That's happened quite a lot," he says. "And Mike's done it to me a few times as well. If I can't win it then there's nobody I would rather see win than my brother. But I don't apologise to him if I win, if that's what you mean.
"When we were younger I used to look after him. We've got another brother in between, and I saw Mike as my kid brother. But he's a big boy now and he's beaten me enough times now, especially in the past few years."
Britain could do with both of them performing well in Atlanta, especially after the paucity of golden successexperienced so far. Despite the much- publicised concerns about the heat and humidity, the Whitakers insist that there will be no excuses.
"We were dead worried about it," John admits. "But when we got here we were surprised to see how good the conditions were. The facilities are superb and, to be honest, it was as hot in Barcelona and at the world championships in Holland as it is here. When you have to wear what we do it's probably hot competing at the North Pole."
There are two reasons why they have come here to win a gold, either as a team, together with Nick Skelton and Geoff Billington, or as individuals, representing Team Whitaker. First, they are far from satisfied with just a team silver to show from two previous Olympics. "It's a blip we are both aware of," Michael says. "We win events week in, week out, but it is what we do at the Olympics which gets noticed the most."
John takes up the theme. "Let's face it," he begins, with typical Yorkshire pragmatism, "who remembers the silver and bronze medallists within six months of the Olympics?
"I'm not saying either of us would be disappointed with a bronze or a silver," he adds, "but we wouldn't be satisfied."
The other reason for success is for the good of show jumping, a sport that has enjoyed a healthy Olympic tradition for Britain, at least until recently.
"I remember watching Harvey Smith, Marion Mould and David Broome at the Mexico Games," Michael recalls. "I was eight at the time and I thought to myself that I'd like to have a go at that one day."
John remembers those days, too. "People like them really put the sport on the map. On the Continent and in the States the sport is flourishing, but in Britain, although it's not exactly dying, it has lost its edge.
"I know the country needs another gold medal at these Games, but so does the sport, believe me."
Michael could have had a better start on Monday, knocking over three fences and obtaining a surprising refusal on Two Step. "Not very good at all," he says, removing his shades, taking his baseball cap off and scratching his head. "But I can still qualify."
John fared much better, knocking just the one fence down riding Welham. The team event is tomorrow, and the individual final is on Sunday, the last day of the Olympics. It is not within the realms of impossibility, according to the Whitakers, that Britain could emerge with a couple of gold medals.
"No reason at all," swears John. "We're clearly one of the best teams in the world, and both Michael and I, if everything went our way, are more than capable of winning the individual event. We're both up for it, let's just hope that our horses are, too."
So, you're hoping for a win for Team Whitaker, then? "I'd be delighted, especially if it was me," John answers first.
His brother studies him for a second before delivering his riposte. "Yep, I'd agree, except I prefer it if I took the gold."
Now now, boys.Reuse content