When do children learn lying is an option?

I am sure we have all heard that children learn the most from their surroundings, their parents being their first teachers and role models. So, if they learn to lie it is probably because they saw an older person do it. To some extent I agree with that—we should not be telling our spouse to say “tell him I am not home…” over a phone or may be other small harmless lies. Harmless for us but they certainly start looking like a viable option to children if they are also trying to avoid something and they do not see anything wrong with it if their parents do it. But that’s not where they pick up on lying. It happens much before that, when they don’t even know the difference between a truth and a lie.
Ok, let’s try to recollect a memory, where your child did something by mistake such as shattering your crystal vase. You ask as an immediate reaction, “Did you do this?” the child nods a ‘yes’ and then suddenly your pitch is high, you are yelling at the child saying things like “What have you done… Don’t you ever listen… You could have hurt yourself…”” etc. etc.
Yes, you were probably not worried about the vase and more worried about the child getting hurt but were you able to see your child’s face. The child is scared not because of the vase breaking but because of your loud voice and may be even your facial expression. Normally I have seen in such cases the child runs and tries to hide behind the parent who is not or less angry.
You see the child is scared and empathize. It’s all done and we all move on, but not our babies. They store the memory of an over-anxious and angry you and if any such situation gets repeated, they get scared even before you reach the scene. You again ask the child did you do this, the child is scared and not able to respond. Interestingly we are angry but not with the child because we feel this was not done by the child and the child can see that. This is when they realize that if my parents do not know I have done it, they are not angry with me. Next time around you ask did you do it, they will nod a no and confirm their theory.
So the most important thing is if you do not want your child to lie, is  not to react negatively if the child tells you the truth.
Also, since the child has stepped out of the confines of the home, is meeting more children and adults alike, they imbibe a lot of things from the environment also. At this point it is very important to keep a check if your child is picking up on lying.
The first hints would be the body language. I am not an expert on body language but having read a few books, I saw those signs come to life. Our bodies are not designed to lie (for that matter do anything that is morally incorrect), so when we do lie or at the least when we start to lie, our body tries to stop us from lying. As a reaction, hands try to cover the mouth as the child start to speak a lie, with time this hand moves to nose, cheeks or forehead etc. Try to catch this sign as soon as you can. There are other things like a change in tone or pace of speech, a flicker in the eye, repeating the same stuff, avoiding eye contact, hands in the pocket or behind the back, a little fumbling, and etc. But you want to catch these signals as soon as possible because with time the poker face becomes strong and the lie learns to control the body and minimize these signals.
You could also try asking the same question in different manner, just don’t let suspicion control your sound and try to look for inconsistencies in response. At the same time, have faith in your children, believe in them. Let them know you believe in them and how that makes it important for them to speak the truth every single time.
But, assume you did everything but you still find out the child lied, it is very important how you react in such a situation. There are two very important aspects to this. First do not embarrass the child at all specially in presence of others and secondly try to find why the child was forced to lie. Talk to the child, make him/her feel secure (they are definitely scared of something that made them lie), find the root cause and ensure that the child understands he/she can talk to you however bad the situation is and that their fear was just their assumption and whatever made them lie, is not the reality. Also while you are explaining or talking to the child the most important virtue is patience. They may take time to open up and if lose your patience, it would be like 2 steps forward and 4 backwards.
Try to convert mistakes to learnings, both for yourself and your child. They may have spilled a jar of beans. Collect it and make a food pot for the birds, teach your child how important food is and how these birds work all day to collect 1 bean at a time.
Okay, now what if the child tells you a truth and it is bitter, you don’t like it at all. How do you react to that? That is tricky, really. You taught them to never lie and make sure that continues. Again no negative reaction, the first thing to do is reinforce they did the right thing by speaking the truth. Tell them you understand it is not an easy thing to say and you appreciate their habit of telling the truth.
All in all we can take the following pointers:
1.    Exercise patience, specially on losing control
2.    Keep a check on your children’s body language and look for sudden changes
3.    Try asking same questions in different manners but politely every time
4.    Talk to them to understand why they lied
5.    Believe in your children
6.    Convert mistakes to learning opportunities
7.    Appreciate your child speaking truth
8.    Finally be the role model and do not lie

Though there is no bottomline to parenting, these pointers above are very much achievable.