Do you mean through chemical reactions, or randomly? One of these things is not like the other...
"Do you mean through chemical reactions, or randomly? One of these things is not like the other..." - ThinkPlease
You are sadly missing the point. It's not that chemical reactions are "random" or not, it's how chemical reactions sequence data that matters.
The author's math effectively covers the sequencing of data, be it via magnetism on your hard drive, chemical reactions forming DNA strands, monkeys pounding letters to quote Shakespeare by accident, et al.