The siblings grew up keeping hamsters, guinea pigs and mice in a special dollhouse at their home in Bel Air, and the rodent hotel was even fitted out with water and electricity for their pets.
Speaking about their unusual idea of fun during their childhood, Nicky said: "We liked rodents: hamsters, guinea pigs, mice ... all rodents, it's very strange looking back now."
Whilst Paris added: "Yes, we took them to our home in Bel Air, California. There we had a huge dollhouse, it had a living room, bedroom and kitchen. There was also water and electricity. It was gorgeous. We hid them there, so we didn't upset our parents, who knew nothing about it."
Paris and Nicky have always been close and are never "competitive" with each other.
Talking about their sibling bond, Paris shared: "We have never actually been competitive with anyone. We have always wanted the best for us, for our friends, for everyone in the world. And I think this is a wonderful way of being: because what you give, you receive. And I'm very lucky, my sister is also my best friend, I don't know what I would do without her."