Cindy Crawford doesn't ''understand'' social media.

The 49-year-old model's 16-year-old son Presley Gerber started posting photos of his 13-year-old sister Kaia Gerber - who was recently signed to IMG as a model - to Instagram in 2014 and even though she doesn't use the photo-sharing app herself, she thinks the way her children uses it is ''cool''.

Asked whether she was surprised by her kids' Instagram success, she said: ''It's so funny, I just don't understand that whole world yet. But, I guess yes and no. Just the way the world works - for me when he started taking pictures of her, the greatest thing about that was that they were doing something together, and I thought it was cool because he's her brother.''

The brunette beauty - who is married to Rande Gerber - went on to confess she feels like MTV was her equivalent of social media, as appearing on 'House of Style' is what made her famous.

Speaking to Harper's Bazaar magazine, she explained: ''In some ways, I feel like MTV was my social media ... When I got to do MTV, all of a sudden I got to bring my personality a little bit more, and I think I enjoyed that aspect.

''I feel like I would have liked it (social media), it's a direct communication with the world and it goes two ways. It's not just you putting out stuff, but since I didn't grow up with it, sometimes I do feel, 'Ugh do I really have to tweet about it?' And someone's like, 'You need a Pinterest' and I'm like, 'Who has time for all this?'''