Yes, all living things contain DNA, with the exception of some viruses.

Here's why:

* DNA is the blueprint of life: It holds the genetic instructions for building and maintaining an organism.

* Viruses are a special case: While they carry genetic information, they don't have the machinery to replicate on their own and need a host cell to reproduce. Some viruses use RNA (ribonucleic acid) as their genetic material, rather than DNA.

So, while there are exceptions, DNA is the fundamental building block of life for the vast majority of living organisms.