Crawford, 49, said she teases the 14-year-old girl of having her old legs, reported E! online.
"I do and I'm really jealous. No, I'm joking. I always tease her 'You have my old legs. Give them back,'" she said.
The brunette model says her two children, Gerber and her older brother Presley Gerber, 16, have helped her age with grace.
"I think honestly I am probably the hardest on myself. It's beautiful as a mother to watch your children grow up and become whoever they're going to be and I think that makes it easier for me to watch myself also getting older," she said.