Alice + Olivia By Stacey Bendet - Arrivals - Spring 2016 New York Fashion Week: The Shows
Credit: Michael Loccisano/Getty Images

There's no bond like the bond between sisters, and Paris Hilton just proved that her baby sis, Nicky Hilton Rothschild, has been her best friend since birth.

Hilton took to Instagram to wish her younger sibling a happy birthday by posting not one, but two unbelievably cute photos (below) from their childhood. The first picture is a throwback Polaroid of the two during Rothschild's fourth birthday. She included in the caption for the first birthday wish, writing "So lucky to have such an amazing sister. I am so proud of you & look up to you so much. Wishing you the best on your special day! I love you sis!"

For the second gram, Hilton posted an even older photo of herself holding Rothschild when she was still a newborn. She confessed that her little sister was, "My first baby doll," in the caption, and summed up the text by typing, "I was so excited when my mom brought home my new little sister." It doesn't get any cuter than that.