This page lists fan theories about the television series Hey Arnold!.
Phil & Gertie are Arnold's parentsEdit
In the show, Arnold believes that he is an orphan. In reality, he is actually the child of Gertie and Phil, whom he calls his grandparents. Gertie and Phil are mentally unstable and told Arnold that his real parents died in a plane crash so that he would not figure out that their old age is what gave him his health conditions. One is hydrocephalus, the reason for his oddly shaped head. He also suffers from the Arnold Chiari Syndrome (hence why his name is Arnold); as he is bullied, he has imagined an imaginary world with imaginary friends. This is the reason they all have weird shaped heads. It makes him feel like he is normal, and no one can pick on him because of his head.