A surprise from my son

Well, my toddler son surprised me a few days ago by saying "xiexie baba" , which means "thank you, dad" in English. You might think it was just a little bit trivial. But it was his first time to say "thank you". You may not know this, but traditionally Chinese people don't or very seldom say "Thank you" to their parents and offspring. For instance, I can't remember when I said this to my parents last time (I can't remember the last time I said this to my parents). As for my son, he is just three years old (这里不需要 "-" hyphens，because this phrase isn't being used as an adjective). My wife and I have been trying our best to improve his vocabulary, and teach him other skills, for example how to distinguish colors. But we have failed to educate him on how to interact with others. I mean we haven't told him how to say daily language, such as "thank you", "I am sorry" , or "please" . 

But that time, when I had bought him a remote-control car which he had been looking forward to for a long time, he was immediately over the moon and said "thank you" . I was not sure who he had learnt that from. I suppose he might have learnt from his cousin who is a teenage girl and had been with him since the previous week a week before.
As a matter of fact, I was as happy as he was at the moment. I think when my son grows up, he will live in a new world where he will have an easier life than mine. Without doubt, before stepping into society, what he should do is learn how to deal with personal relationships. And I believe that his saying "thank you" must be a wonderful start.

a three-year-old boy

The boy is three years old.