Selection pressure creates the complexity. Aside from what is selected for (the ~50MB of genome), where does the extra complexity come from? Why is it there? There's no reason why selection pressure would concentrate any complexity in the extra-genomic data rather than the genome itself. In other words, most of the complexity of the initiator mechanisms is redundant in the genome itself, aside from that crucial bit to translate from genome to vehicle which is simply carried over trivially from one generation to the next. The rest is probably the substrate data, I.E. behavior of molecules in general.

As an example: What "state" that makes sense of the genome is encoded in, say, mitochondria?

What "state" that makes sense of the human genome is stored in, say, symbiotic bacteria that we host?

Does that make sense to you?

It is a reasonable assumption that the other genomes involved in human development are selected for as well, but don't drastically multiply the overall complexity of humans and especially not for the brain's design. Thus the issue is still how complex extra-genomic data is such as the preexisting cells which actuate DNA, which is what I addressed.