Original: Little is known of Mario's childhood, though the infant version of Mario, Baby Mario, first appeared in 1995 in Super Mario World 2: Yoshi's Island, and has often appeared in Nintendo sports games since that time.
Simplified: Baby Mario is the infant version of Mario. He first appeared in Super Mario World 2: Yoshi's Island, released in 1995 for the Super Nintendo Entertainment System, and has appeared in several titles since.