Although MTV doesn't appear to have shown the actual birth, they do have plenty of footage for fans from the moments following Lincoln's arrival -- which happened a whopping 16 hours after Kail first went into labor.
After meeting his little brother for the first time, Isaac says, "Mommy look, he's a baby! Look at his eyes. His eyes!"
Then, when Kail says that Isaac and Lincoln are her babies, Isaac tells her, "No, he's my baby."
From the sound of things, Isaac was thrilled to welcome his little brother. However, he wasn't a fan of the little one's hair, and told Kail, "Mommy, his hair is disgusting."
For more of Kail Lowry and adorable Isaac, tune into "Teen Mom 2" every Tuesday at 10 p.m.