Three of the world's 10 youngest billionaires can trace their wealth back to the seafood industry -- salmon farming in particular.

Norwegian heiresses Alexandra and Katharina Andresen, daughters of multi-billionaire investor Johan Andresen, are the world's second- and third-youngest billionaires, according to a new Forbes ranking, just behind reality TV star Kylie Jenner.

The Andresens hold estimated assets of $1.1 billion (€1 billion), according to Forbes, via their inheritance in the family's Ferd investment group.