The UK is now the most prolific winner of the short sprint, yet not one of these athletes has gone on to claim an individual senior global medal, far less a title.
Prodigious Scottish junior talents have also failed to make an individual impact. Gemili's time of 10.05 seconds in Barcelona this week was a championship record and British junior best, prompting extravagant speculation that he may become the first junior ever to go under 10 seconds.
That chance may come at the Olympics. However, history suggests he will struggle to graduate to senior title status. Only two world junior sprint champions have repeated this as seniors, and Britain is notoriously poor at developing young talent.
Since the world junior event was inaugurated, Scotland has had two sprint bronze medallists (Jamie Henderson at 100m and Ian Mackie, over 200m). Neither won a senior world medal. The career of Elliott Bunney, who preceded Henderson as European junior 100m champion, predated the inaugural world junior event. Although Bunney won Olympic silver, it was with the 4 x 100m quartet in Seoul. He, too, never won an individual global medal.
Bunney is equal third- fastest Scot ever, at 10.20, while Henderson is just one hundredth behind. He was GB senior champion as a schoolboy, such a raw novice at the time that he did not possess a tracksuit and wore his Edinburgh Academy cricket sweater. He clocked 10.21 as a junior, but ran no faster as a senior.
Gemili follows Christian Malcolm (1998), Mark Lewis-Francis (2000), and Harry Aikines-Aryeety (2006) in winning world junior 100m gold. Welshman Malcolm also won the 200m title, setting championship records at both distances. A veteran of seven Olympic and world outdoor championships, he has reached the final on just three occasions, without taking a medal. Now he is heading for his third Olympics.
Lewis-Francis won world youth and junior 100m titles, plus European junior gold, but has never featured in a world or Olympic 100m final, though he was part of the GB gold medal-winning Olympic relay quartet in 2004.
Aikines-Areetey, also world youth and junior champion, has thus far failed to translate his prowess to the senior stage. Now 23, he did not achieve selection for London.
Britain's high sprint achievers have a poor record of stepping up at global level, though Colin Jackson, world junior hurdles champion, did make it to world champion and world record holder.
It is interesting to note that, conversely, future high sprint achievers are often also-rans at junior level. When Aikines-Areetey achieved his world youth 100/200m double in 2005, Yohan Blake was seventh in the 100m final. When Aikines-Areetey won world junior 100m gold in 2006, Blake was third.
Yet Blake beat the world 100m record holder Usain Bolt when his Jamaican compatriot false-started at the World Championships last year in Daegu, and then beat him fair and square in the Jamaican Olympic trials. Despite Bolt's palmares, it's Blake who is now the form horse for the blue riband sprint in London.
A further intriguing footnote is that the only Jamaican in the all-time junior top 25 at 100m is Blake. In 25th place. And though Bolt is fastest-ever junior at 200m, he is the sole Jamaican in the top 20.
Among the only ranked US juniors to graduate to Olympic champion, Justin Gatlin 17th-fastest while Tim Montgomery was 24. And both were later convicted drug cheats. Extreme junior prodigy rarely translates to senior glory.
It is as if prodigious junior performers achieve because of freakish development, and that when their peers reach their maturity at a later date, they catch up and often surpass. There is also the consideration that the prodigious young get it easy, while those they beat hate the experience, and develop the work ethic to ensure it does not happen in future. Blake is known as "The Beast" for the strength of his work ethic.
The world junior 100m best is 10.01, set by Trinidad's Darrel Brown, who won world junior gold in 2002. Brown went on to post a career-best of 9.99 but his only senior global medal was world 100m silver. It's also worth noting that drug-tainted Dwain Chambers set a world junior 100m best of 10.06 in 1997, and won European junior 100m gold in 1995 and 1997, yet he was a modest fifth in his only world junior 100m appearance, in 1996. However, he went on to reach three world 100m finals (bronze, 1999) and one Olympic final (fourth).
The fastest UK and Scottish 100m men, Linford Christie and Allan Wells respectively, did not feature as juniors. Wells was the then oldest Olympic 100m champion in 1980, aged 28; Christie ditto at 32, in 1992.
Darren Campell, second in the world junior 100m and 200m behind Ato Boldon in 1992 might claim to be the UK exception. He reached two world and two Olympic finals, denied 200m gold by the Greek drug cheat Kostadinos Kenteris in Sydney, and won world 100m bronze in Paris in 2003 in the same time as fourth-placed Chambers.
Boldon, first to achieve the world junior title double, is one of only two men to win junior and senior world sprint crowns, along with Bolt. But Boldon never won Olympic gold, though he did win four individual Olympic medals.
Let's celebrate Gemili's prodigy, but not burden him with expectation.
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