Most people don't go into the attic of their St Louis homes very often to self inspect, I get that, but, you can sometimes see some of what's going on in there from outside, too, if you know what to look for.
It can be pretty obvious on the right day, once you see it. A home that has heat escaping the building envelope, through ceilings and into the attic, will melt a frost or light snow from the roof everywhere except at the overhangs.
This can be a number of different issues in the home's attic: improper installation of insulation, low / settled insulation, even rodent or cable guy displacement of insulation. Other possibilities include exhaust vents from bathrooms or the dryer vent could be not vented fully to the exterior, leaky attic fans, or flexible duct work that often has worked loose at the connection point to the trunk line, or even improper ventalation of the attic as a whole.
When performing Home Inspections in St Louis and St Charles area, I check for all these things, and much more, in your attic.