The family of balloons

The young son of a family of three balloons was sufficiently small for him to sleep with his parents in their bed.
The time came when he became too big to fit in the bed and his father told him to sleep in another bedroom. During the night the son was afraid and went back to his parents but could not fit.
He undid the knot in his father balloon to make him smaller and thus create some space and then re-knotted it. This did not work and he did the same to the mother balloon, still no joy, so he did the same to himself and eventually managed to snuggle in.
The next day the father balloon saw his son and very angry he said, “Son you’ve let me down, your mother down and worst of all you've let yourself down.”