Plus, hear which famous family the Carters share a doctor with!
The mystery behind Rumi and Sir Carter's actual birthday has finally been solved!
After weeks of speculation, ET has obtained the official birth certificates of Beyoncé and JAY-Z's newborn twins.
WATCH: Beyonce Shares First Photo of Twins Sir and Rumi Carter
According to the documents, the precious boy and girl were born on June 13 in Los Angeles, less than a minute apart. Dr. Paul Crane delivered the bey-bies, and if his name sounds familiar, you're not going crazy -- you may have heard about him on Keeping Up With the Kardashians, as he's the same doctor the famous family goes to!
Beyoncé and JAY-Z's daughter, Rumi, was born at 5:13 a.m. PT, while son Sir arrived shortly after. Unlike the power couple's first child, 5-year-old Blue Ivy, the twins do not have middle names.
ET caught up with Queen Bey's mother, Tina Knowles, at the 19th Annual DesignCare hosted by the Hollyrod Foundation in Los Angeles on Saturday, where she not only confirmed the name of her grandbabies, but gave us the scoop on how Blue Ivy is doing as a big sister.
WATCH: Tina Knowles Reveals How Beyonce Is Adjusting to Twins
"She's very proud and very excited," Knowles shared. "She's a good big sister, she really is."
Watch the video below to hear more!