A Parent forum would be something like "ENGINES" A child forum to that would be like "Engine FI, turbo's or the like". So its basically a subsection to a bigger, and more broad topic.
Beyond that, some random off topic discussion involving "Children" (hence those threads came up when you searched). Which is odd for a hot rod forum unless its about driving them around in one.
Last edited by Graham M; 03-16-2013 at 05:59 PM.