Younger siblings can also be inspired to take up the same sports as their older brothers or sisters. “She would always drag me out to run or to kick balls,” Lyon striker Ada Hegerberg, the first women’s winner of the Ballon d’Or in 2018, said of playing with sister Andrine, two years her elder.
Midfielder Andrine, who spent two years at Birmingham City in 2016-18, now plays for Roma. “The bond that I always have had with my older sister has been crucial for everything I have done when it comes to training, pushing each other,” Ada added.
Playing with older siblings also harnesses competitiveness. Even as a young child, whatever the game, “She always had to win,” Serena Williams’s mother, Oracene Price, recalled.
Older siblings give young children someone to learn from. “I’ve learnt a lot from watching Venus,” Serena said in 1998. Two or more people working together to learn a particular task, which is called dyadic learning, has been shown to be more conducive to learning new skills. Younger siblings benefit especially because they can learn more from their siblings than vice versa.
The little sibling advantage in sport is rooted in how younger siblings are challenged more. The science of this is the optimal challenge point – the sweet spot at which athletes learn skills at the fastest rate, a concept developed by scientists Mark Guadagnoli and Tim Lee. Essentially, athletes learn far more when they fail regularly.
Think of those tennis games between the young Williams sisters. As a child, Serena lost most of the time, but that also meant that she learnt more than Venus.
By playing with their elders, younger siblings learn at an accelerated rate. If older siblings know only victory in their garden games with their younger brothers and sisters, it means they are not learning nearly as much. “If you find that someone has more success than about 70–75 per cent of the time during practice, they’re probably not being stressed appropriately,” Guadagnoli observed. Not all practice is equal; when two siblings play against each other, the younger benefits more.
Younger siblings are forced to develop alternative skills. Because they are generally smaller and less strong, little siblings need other ways – skills, tactics and creativity – if they are to compete. When they have physically matured, little siblings no longer have these physical disadvantages – but they retain their advantages in other areas, helping them perform better than their big brothers or sisters.
In women’s sports, the little sibling effect can be particularly potent in sports that have historically had lower participation among girls. When Steve Knight was 11 he joined the local cricket club; naturally, Heather joined too.
“I think I would have found it quite hard if I didn’t have an older brother to get involved in the game,” she reflects. Looking at the 2017 World Cup squad, “I don’t think a lot of us would have really got involved if we didn’t have older brothers.”
For young girls – or boys – having an older sibling is one of the hidden hands which determine which athletes become the most celebrated. Being born at the right time also helps; athletes old for their year tend to be overrepresented in both youth teams and at senior level – the relative age effect. It is not that September-borns are inherently any better at sport than stragglers born in July and August. But those old for their school year tend to be bigger and stronger – by year six, a child born in September will be 10 per cent older than one born in August – raising their chances of being picked and absorbed into the system.
Some styles of parenting are also more conducive to nurturing greatness. Pushy “Tiger parenting” is damaging both to children’s mental health – excessive parental pressure in sport has been linked with higher anxiety, reduced self-esteem and self-confidence – and to their chances of becoming professional athletes.
A study comparing British “super” champions with “almost” found that the parents of “almosts” were far more consumed by their child’s sporting careers – complaining to the coach about them not being picked or spoiling them with all the best equipment. Mostly, the parents of “super” champions allowed their children to get on with things themselves.