The basic idea of inheritance is that some trait (be it morphological, molecular, embryonic, or behavioral) can be preserved in the form of genes and transmitted faithfully from one generation to another, although mutations can at times occur to generate variations of this trait.
Since all life forms on Earth are thought to have descended from a common ancestor, a large, continuous phylogeny can capture the entire history of life on Earth. If a specific trait arose at any internal node (an ancestral population), that trait is expected to be found in some or all of its descendant populations. The basic mechanism that ensures this pattern is transmission genetics.
For example, meiosis is a trait (character state) for cell division, and it arose in an ancestral population of all eukaryotic life forms (whether extant or extinct). Meiosis was capable of being inherited by all descendants of this ancestral eukaryotic population because it was regulated by genes. As long as these genes were inherited, and life forms expressing these genes withstood the test of natural selection, meiosis was successfully inherited and propagated.
Thus comes a question, if a trait is not preserved by genes, what other factors or forces would ensure its faithful inheritance from one generation to another? (A reasonable degree of variations always accompanies intergenerational inheritance, but it can be ignored here.) The most obvious example is the genetic code, which is part of the central dogma of molecular biology that governs the transcription and translation of genes.
It is postulated that the genetic code has existed since the Last Universal Common Ancestor (LUCA). Without genes that preserve the genetic code, how could the genetic code have been inherited and propagated throughout all life forms on Earth?