Celebrity Parents 'Duck Dynasty' 's John Luke Robertson, Wife Mary Kate Welcome Baby Girl Ella Kathryn: 'So Thankful' John Luke Robertson and Mary Kate Robertson are also parents to son John Shepherd, 18 months By Benjamin VanHoose Benjamin VanHoose Twitter Benjamin VanHoose is an Associate Editor on the Movies team at PEOPLE. He's worked at PEOPLE for over three years as a writer and reporter across our Entertainment, Lifestyle and News teams, covering everything from the Johnny Depp v. Amber Heard trial to the Oscars. He regularly covers red carpet events and has interviewed stars like Drew Barrymore, Ryan Reynolds and Kirsten Dunst. He previously worked as a copy editor at Topix Media Lab. People Editorial Guidelines Published on April 13, 2021 12:42 PM Share Tweet Pin Email Photo: John Luke Robertson/Instagram The dynasty is expanding! Duck Dynasty star John Luke Robertson and wife Mary Kate Robertson welcomed their second baby together, daughter Ella Kathryn Robertson, on Thursday, April 8, they announced on Instagram Monday. The pair are also parents to son John Shepherd, 18 months. "Our precious Ella Kathryn! She was born Thursday morning, 4/8/21, and it was just the sweetest, most peaceful, joy-filled delivery and day. We are so thankful for this little blessing!" wrote the mom, sharing a pair of photos of the newborn. John Luke, 25, shared a photo of himself smiling alongside his wife and baby girl, writing, "Welcome to the world baby Ella! You are sooo cute!! Good to have a child that looks like me!" Want to get the biggest stories from PEOPLE every weekday? Subscribe to our new podcast, PEOPLE Every Day, to get the essential celebrity, entertainment and human interest news stories Monday through Friday. John Luke Robertson/Instagram RELATED GALLERY: Celebrity Babies Born in 2021 (So Far!) The reality stars tied the knot on June 27, 2015, after John Luke popped the question the previous October (on his 19th birthday), presenting his then-wife-to-be with a photo album that included a picture of her engagement ring on the last page. RELATED VIDEO: Sadie Robertson Expecting First Baby with Husband Christian Huff: 'Screaming with Excitement!' RELATED GALLERY: Who's Due Next? Celebs Who Are Expecting Celebrating their firstborn's 1st birthday in October, Mary Kate called her baby boy "the most beautiful, precious gift God has ever given us." She added at the time, "It's been so fun watching you grow this year into a smiley, curious, happy, snuggly little boy!" The couple then revealed their pregnancy news in November, with the expectant mom writing on Instagram, "We are so incredibly excited to be welcoming another sweet baby into our family!!! This new life is such a gift we are so thankful for! Sheps going to be the sweetest big brother." In his announcement, John Luke wrote simply, "Round 2."