Unfortunately, my language skills barely allow me to cope with my native tongue--my attempts at other langauges have mostly either been humorous or a disaster--so I cannot offer you its etymology.

I googled for define:behaviour. The first definition listed is:

behavior: the action or reaction of something (as a machine or substance) under specified circumstances;

Behaviour is also not confined to use with concrete things like machines and people; it's not uncommon in our industry to talk of "well behaved algorithms"; and chemists talk of "well behaved reactions".