Cindy Crawford and her daughter, Kaia Gerber, were twins back in the day, too!

The supermodel took to Instagram on Saturday, Sept. 3 to wish her little girl a happy 15th birthday with a cute throwback snapshot of the two — and they look so alike in the pic!

"Happy 15th Birthday to my little girl! Kaia Gerber, you make us so proud every day and we love you so much!" the 51-year-old captioned the vintage photo.

MORE: Cindy Crawford's Daughter Kaia Gerber Admits She and Her Mother are Twins

Cindy and her husband, Rande Gerber — who married in May 1998 — welcomed Kaia in September 2001. The duo are also parents to a 17-year-old son, Presley, who was born in July 1999.

Click through the gallery to see more photos of Cindy and Kaia looking like twins!