Strange Glitch, or Something Else?

I recently noticed a weird problem: whenever I try to move/scale/rotate an object, other objects that share the selected object’s center (even if they are NOT selected) will also be transformed. For example, say I have a sphere located at (0, 0, 1) and a cube located at (0, 0, 1). If I select ONLY the cube and try to scale it, the sphere also gets scaled. If the sphere is located anywhere else, say (0, 0, 1.1), the sphere will not be scaled. I cannot figure out why this happens; I have never had this problem until today.

I am doing this in blender game, with version 2.78b. I have also found out that if I open a new blender file, this problem does not occur. It only happens in some files that already have stuff in them, so I suspect I may have accidentally changed some setting somewhere. Please help me figure this out!

Turn off proportional editing

That worked, thank you so much!