Question

You never give your employees gifts, but one of your employees always gives you gifts for holidays, birthdays, and boss' day. is it wrong for you to accept these gifts?

Answer 1

That depends. Is it against your faith to take part in holidays and birthday events? If so then yes it is wrong and explain your beliefs so that they bother you with that no more.

Answer 2

Technically speaking, it won't be wrong for you to accept the gifts.

You never giving any of your employees gifts show that you gave no 'special favor' to specific employees. It's a matter of ethical belief and your personal action
But you can't control other people's ethical belief, just like you can't control other people action's