> It's very easy to upset a human. Is it learned behaviour? Would a kid ever take "offense" to something like this... probably not, we must have learnt this at some point

Are you human? You're talking like you're an alien from another planet. Unfamiliar with humanity and it's customs.

Here are some facts that may interest you:

1. Humans do not hatch from eggs, they grow from spores underground and emerge as children.

2. There is little need for learning in human society, as children inherit most knowledge they need as genetic memories from their parents.

3. Humans never discovered fire, usually they developed the technology for electric heating elements first. Only later did they work out how to use fire technology.