If you talk back to your mother, your hand will fall off.
The subject told me that when she was young her mother told her a lot of different superstitions to get her to behave. One of the ones she used the most often was the above, which was about talking back to your mother and how your hand will fall off as a result. I asked her why it was the hand, and she said it came from the idea that if you raise your hand at her, then you will be punished by losing your hand. She did not know the origins of the saying exactly, however it was not only her mother who used it, as another subject said that her mother would say it to her as well. I asked if the superstition prevented her from talking back to her mother, and she said that for awhile it really scared her, but as she grew older she began to realize that it was not true and ignored it.
I think that this superstition is clearly created to keep children in line. At first I did not see the connection between losing a hand and talking back to your mother, however after she clarified it, explaining the act of raising your hand at your mother it made much more sense. I think that this idea of behaving towards your parents reflects the common Mexican tradition of respecting your elders. Mexican culture is very community and family-oriented, where the grandmother and grandfather expect to be taken care of by their sons and daughters, often residing in the same house. To typical Americans this sound preposterous, however Mexican tradition puts a high value on the elders and their wisdom. This idea that talking back to your mother would cause you physical harm is not so much about the harm as it is about teaching the child to respect their parents and eventually to care for them in the future.