[Obi_Juan_Kenobi]

A gene is essentially defined as having a gene product, either an RNA or protein. So yes, all genes are functional.

Genes that aren't translated into protein sequences (noncoding genes) can create structural RNAs as with Ribosomes, microRNAs that have regulatory functions, etc.

There are lots of non-gene genetic elements that do things, though. Many are involved in gene regulation, affecting the transcription rates of nearby loci through a variety of mechanisms. There are also vast swaths of inactivated transposons, retroviruses, and other repetitive genetic sequence.