The practice of "gift giving" between the parties to a business negotiation is considered right and proper behavior in many asian cultures. however, some westerners view the practice as a form of bribery, and therefore unethical, particularly if the gifts are substantial. this reflects that:

I believe the answer is: what is ethical depends on one's cultural perspective

Cultural value that a certain society had would determine the things that considered to be right and the things that considered to be wrong by that society.

Different cultures would mean that the standard of what considered as right or wrong might be different. It is important for business person to study the foreign culture before initiating gesture like this in order to avoid offending the people from other cultures.

the branch of biology that deals with the normal functions of living organisms and their parts.

the way in which a living organism or bodily part functions.