South Carolina-born Lurie Poston was only 12 years old when he was cast as the sharp singing son Tommy -- who nails his part in the family a cappella rendition of the Guns N' Roses jam "Sweet Child O' Mine" -- in the 2008 sibling comedy "Step Brothers" With Will Ferrell and John C. Reilly.
Lurie Poston belted out the tune with his onscreen family including Elizabeth Yozamp as the on-key little sister Tiffany, Kathryn Hahn as the mom who wastes $1,200 a week on singing lessons Alice ... and of course the wild-driving dad who almost kills the solo Derek.
Guess what Lurie looks like now at 23 years old!