People.com Celebrity Parents Kendall Jenner on How She Found Out About Kylie's Pregnancy, Says Brother Burt Jenner Is Expecting "I wasn't really shocked because I felt like it could happen someday soon, but I was excited," Kendall Jenner said on The Tonight Show By Naledi Ushe Naledi Ushe Digital News Writer, PEOPLE People Editorial Guidelines Published on September 15, 2021 09:16 AM Share Tweet Pin Email Kendall Jenner is excited to be an aunt of 20! While appearing on The Tonight Show Tuesday, the 25-year-old model opened up about the moment she learned her younger sister Kylie Jenner was pregnant with her second child with Travis Scott and confirmed her older brother Burt Jenner is expecting a third child with longtime girlfriend Valerie Pitalo. "[Kylie] called me, and I answered the phone and she just had her little sonogram — a picture of the sonogram," Kendall told host Jimmy Fallon of how her sister shared the news. "I wasn't really shocked because I felt like it could happen someday soon, but I was excited. It's just a blessing." Kendall Jenner Does a 'Naked Dress' Take on an Iconic Audrey Hepburn Look at the 2021 Met Gala As her siblings expand their families, Jenner looks forward to becoming an aunt twice more. Alex Hooks/NBC/NBCU Photo Bank via Getty Images "There is 18 of them now, going on 20," she added of her nieces and nephews. "There's two on the way. My brother Burt has one on the way and then my sister obviously just announced hers." Last month, TMZ reported that Burt, 43, is expecting a third child after Caitlyn Jenner told the outlet she has a 19th grandchild "in the oven." That same month, multiple sources confirmed to PEOPLE that Kylie and Scott, 30, were expecting their second child together. "Kylie is a few months along. She has a cute bump. She is beyond excited," a source told PEOPLE of the happy news, adding that the beauty mogul had been spending time with loved ones away from the public eye during her early pregnancy. "She has been wanting to give Stormi a sibling for a while. She loves being a mom. She is thrilled that she and Travis are pregnant again," the source said. "She has been enjoying her pregnancy in private. She has only spent time with close friends and family." Kim Kardashian and Sisters Congratulate Kylie Jenner on Second Pregnancy: 'More Babies! More Cousins!' The Kylie Cosmetics mogul later shared a sweet video announcing her pregnancy, featuring the touching moments she told Scott and her mother Kris Jenner she was expecting. Kendall and Kylie Jenner. Dimitrios Kambouris/Getty Images During her older sister's recent appearance on The Tonight Show, Kendall spoke about being "the cool aunt" and described herself as an "alright" babysitter. "I always wanted to be the cool aunt and I guess liked by all of them," she explained. "I have a lot of them, but it's fun. It's really fun. I try and be chill." Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. What's more, the Keeping Up with the Kardashians alum said Kylie's 3-year-old daughter Stormi especially loves to see her lately, because she brings her boyfriend Devin Booker around. "Him and Stormi have an amazing relationship," Kendall told Fallon, 46, of her NBA player beau's adorable bond with her niece. "She has the biggest crush on him, and I'm jealous sometimes. I'm like, 'Stop – can you guys not?'