Hold up — Catelynn Lowell and Tyler Baltierra‘s daughter, Carly, has a brother?! The now eight-year-old, who was placed for adoption by her then-teenage parents in 2009, has a lil’ sib, and we had no idea!

Back in 2012, the Teen Mom OG stars revealed that Brandon and Teresa — who adopted Carly — also adopted a little boy, which made Carly the first original Teen Mom baby to gain a younger sibling. At the time, Catelynn was also working closely with Bethany Christian Services, the adoption agency that handled Carly’s adoption, to help provide emotional support and advice to expecting moms considering adoption, and one of the women she was working with was Carly’s little brother’s birth mom.

During a discussion with Cate and Tyler’s adoption counselor, Dawn Baker, Cate said, “Her name is Beth, and she’s a little bit older than me, and she was carrying a son, and a dad was not involved, and she was all by herself,” she revealed in a transcript provided to Starcasm at the time. Mom kind of like my mom, but not so bad… she was pretty much living in her car and I felt bad for her. And she was making this greatest decision… But what made me even closer to her is because she was carrying Carly’s little brother. And so that was very special to me.”

She added that she was alongside Beth when she gave birth. “Me and Dawn were there [during] labor — I was holding her leg, I watched that little boy take the very first breath, and you know, I was just there to support her and tell her how I felt and express my feelings, and she really connected with me because it’s the same family. She met them and I was hanging out with them all together with Carly and her, and it was the most amazing thing to watch.” She continued, “You know, I watched my daughter being born and her being placed with Brandon and Teresa, but then again, I got to sit back and watch Carly’s little brother be born and placed with them.” Amazing!

Teen Mom OG airs Mondays at 9 p.m. EST on MTV.

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Cate gives an update on daughter, Nova. Watch the video below for more!