Everybody here is drowning in their conspiracy theories...it's just culture.
Why do we shake hands, other than to give the other person our germs so that if I have a deadly disease the other guy will die too? Well maybe because it's just established. To show that you have respect for the other party, even that you are willing to follow customs. Calm down everyone!
"Culture" is just a set of practices and assumptions that have been internalized - talking about where they came from is anthropology/history. You can certainly have conspiracy theories in there, but you seem to have confused those with any explanation at all.
Why do we shake hands, other than to give the other person our germs so that if I have a deadly disease the other guy will die too? Well maybe because it's just established. To show that you have respect for the other party, even that you are willing to follow customs. Calm down everyone!