If Christ were joy, Antichrist would be bitterness. No matter the skill or technique, as a painting done in bitterness leaves its scars on the canvas, so parenting done in bitterness will leave its strokes on the canvas of the soul. It is rottenness to the bones. It doesn't matter why a parent is unhappy. The parent need not be unhappy about the child, but any unhappiness becomes the child's bread all the same.
Positive creativity is conceived in the womb of joy.
God created humans to be happy. Happiness and joy are a healing balm. Joyfulness smiles away all the wrinkles on children's attitudes. Children who rise up a little grumpy and meet a smiling mother are soon smiling with her. On the other hand, children who rise up grumpy and meet a grump will spiral downward into the pit of misery.