I'm used to handshakes for non blood related males (friends, business contacts) and kisses in the cheeks for relatives and females.

In Anglo-Saxon and Germanic countries women default to the handshake even outside of business settings. I find it odd and still have difficulties adjusting to that.

Hehe as someone from Germany living in Sweden, I find this constant cheek kissing with quasi strangers in Southern or Western Europe or the Spanish speaking world pretty akward. But I understand that it's feels normal to most who grew up with it.

It's strange because it's unhygenic but a strong "social lock in" makes it essentially impossible to abstain without sending the signal of being socially awkward.

As a social construct, there'd be no need for going through the procedure, yet everyone basically has to go through it because everyone else does.

Considering that there are plenty of cultures in which handshakes are not commom (like in many Asian countries), there doesn't seem to be any good justification why it's done elsewhere, other than "custom". But not every custom actually is reasonable.

Not that unhygienic and also a pretty straight forward way to dedicate the presence toward another person.

Obviously it's a custom, but I don't see how it is a weird one.