Answer: DNA and RNA
Explanation:
1. When the riddle says "both have no direct relationship", it refers to that although DNA and RNA work hand in hand, they have large differences that help them complement and function.
2. When we talk about "a free efficient expression binds them" we refer to gene expression. It is the process that allows you to obtain proteins from genes, whose final stage is the synthesis of proteins, which binds both DNA and RNA.