How to train your child?

We are definitely not expert, but today i was talking to one of my customer, i realise how obedient and discipline Abby is.
My customer was telling me that her 2 years old daughter was very rude, to the extend that she even bit her grandmother...but did he realise that children are a reflection on our behaviour?
I believe he did not give her enough attention, one of the worst nanny we can have is television, and this is precisly what he is doing with his daughter. He is allowing her to watch TV programmes that may not be suitable for her.
Another thing i realise was that he will do anything to live an easy life now, he allows her to wear diapers, allows her to eat sweet just to stop her from crying, and did he stop her or correct her when she talks loudly or scolds his mother??
He will passes on easy now, but when her children grows up 10 years later, the problem will be compounded, untill then he will be too late to correct them..
Nightmare begins..