Bio relative is a term used to describe a person who is related to another person through biological means. It can refer to a parent, sibling, grandparent, aunt, uncle, cousin, or any other relative that is connected by blood. The term 'chem' is a four-letter abbreviation for the word 'chemical, ' which is used to describe the substances that make up living organisms. In this context, it could refer to the chemical makeup of a person's DNA, which is what determines their biological relationship to another person.