It's long been thought that a stressful life can make a person's hair turn grey.
But a new study has found that grey hair could also be down to our inherited genes.
Scientists at University College London have discovered the first gene for turning hair grey, meaning that some men and women may be more likely to go grey than others if they are born with it.
The researchers have said the gene, known as IRF4, could hold the key to developing new ways to delay grey hair in the future.
The researchers found the gene by analysing the DNA of 6,357 people who live across five countries in Latin America – Brazil, Colombia, Chile, Mexico and Peru. They included people with European, African and native American ancestry.
They found the gene IRF4 was associated with grey hair, but noted that more research is needed into the way that it works.
"We already know several genes involved in balding and hair colour but this is the first time a gene for greying has been identified in humans, as well as other genes influencing hair shape and density," lead author Dr Kaustubh Adhikari said in a statement.
"It was only possible because we analysed a diverse melting pot of people, which hasn’t been done before on this scale."
The scientists found additional genes associated with hair including EDAR for beard thickness and hair shape, FOXL2 for eyebrow thickness and PAX3 for monobrow prevalence.
Dr Adhikari added that the findings could pave the way for new hair treatments in the future.
He said: "These findings have potential forensic and cosmetic applications as we increase our knowledge on how genes influence the way we look."
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