My 10 year old son is very respectful and lovely with everyone but me, his mother! He can be objectionable at times with no apparent reason. I have read all the books on how I should respond etc but to no avail. He is foul with his 4 year old half brother and as I am bringing them up on my own its a struggle! I work with families from very difficult background therefore I am quite diplomatic. Where have I gone wrong?
you are not going wrong. You are doing something right as he is pleasant to others, so knows how to behave. Unfortunately people are most comfortable at home and it is very easy to be rude to our nearest and dearest. It is very common for family members to treat each other like this. Not just children either, sadly. The mantra in our house is to treat others the way you want to be treated. It seems never ending. My youngest can be so horrible to his siblings, then they 'get him back' and off we go.....all bloody day. Unless we have visitors.
You haven't gone wrong anywhere. In his teens, my DS1 was lovely at home, smiley and helpful - but bloody awful at school. My DD was a living saint at school, adored by her teachers, and horrendous at home. Same parents, same parenting approach to each - they just responded differently to those teenage hormones, and I'm guessing your son is pre-pubescent.
It will pass - pick your battles (sometimes it's to everyone's benefit if you just walk away) but consistent, zero-tolerance responses when lines are crossed. What sanctions do you have? I found the removal of pocket money most effective when mine were that sort of age.