What is the cause for low voltage when the breaker is off?
Your thoughts about induced voltage is correct when wires are run in parallel the field created on the live wires induces voltages on the conductors of the other circuits (this is how transformers work). Non contact meters read the field voltage and most hand held meters are high impedance so they will also show voltages. A low impedance or low Z meter creates enough of a load to eliminate the "phantom voltages" as many people call them. The voltages you are reading are quite low and nothing to be concerned about.