I just happened upon an article wherein Deepak Chopra says the following:
Adopt a growth mindset. Chopra says research over the past five years has shown that when adversity strikes, happier people tend to see creative opportunities, while unhappier people see, well, adversity. "It's programmed through childhood through a phenomenon called mirror neurons," he says. "If you saw people complaining all the time when you were a kid, that's what you do. Your neurons mirror the behavior." To change your mindset, step back and ask yourself, How can I turn this into an opportunity?
Nawwwww, I am fairly certain that this is not what the mirror neuron research shows. Mirror neuron research seems to say that these neuron are primarily Motor neurons which respond primarily to intention and physical action. There is research that discusses response to emotional states and so forth but I have a feeling that you mother's complaint 40 years ago is not a part of the neuronal system.