Sadly I have learned that it starts somewhere between 8 - 10 (depending on how many older siblings they have around to pick it up from). My oldest is 14 and I have to say I very much dislike his presence anymore. The sarcastic words, tones and manners set me off. SOme days I am great and can remain extremly cool and just inform him I will not take it and give him a choice of changing or punishment. I have also talked to him about how he ia perceived and how his actions hurt others. He usually gets it and changes but then evil raises its ugly head again.
I know if we ask our parents they will fill us in on our sarcastic, rude behavior too. We have to stick together and learn that these hormonally driven children of ours are growing up and acting out, just like toddlers, trying to be independant but seeking our guidance along the way.
Also we need to remember you always hurt the ones you really love for some strange reason. I know they never act this way with anyone else so that at least gives me peace.
I plan on having a talk with my son tonight about his sarcasm and his attitude about me. He too makes me out to be an extreme idiot that can not do 1 think right so don't feel alone.
The sad thing is I have to go through this 6 times! WHat was I thinking?????