Whether it comes down to skill level, body shape, or pure accident, anyone who has played a sport will have some memory of how they came to be given a particular role.
Tall and like football? Go and play centre-back. Enjoy rugby union and have a bit of pace? Winger.
Step forward Somerset's Dom Bess, who took 6-28 on his County Championship debut on Tuesday.
How did he come to bowl off-spin?
"I was always a little porker when I was younger, so I never took the long run-up," he said.
"I always took five or six steps and just trotted in."
Bess now has the best figures by a Somerset debutant for 55 years, since Tony Pearson returned 7-63 against Worcestershire in 1961.
But any 'puppy fat' the 19-year-old may have had has long gone, with the help of strength and conditioning coach Darren Veness.
"I met Daz and he made me run a lot, which I'm grateful for now," Bess told BBC Radio Bristol.
"Ask Daz about me, I was always a porker."
'Dad's on holiday and mum was working'
Just a month ago Bess, from Sidmouth, was taking 6-65 for Devon in the Minor Counties Championship as they lost to bottom-of-the-table Oxfordshire - having taken 0-128 on his first-class debut for Somerset against Pakistan in early July.
At Taunton, however, his first two victims were Jonathan Trott and Ian Bell, who have played a combined total of 170 Tests for England.
His family have a strong presence in the sport, with cousins Zac and Josh also representing Devon, but who was at the County Ground to watch his moment of glory?
"Dad was on holiday and mum was working, so I just had my girlfriend, her parents and a couple of my mates (watching)," he said.
"I think dad will be a bit disappointed - he's gone to Greece, somewhere like that, for a week away."