“If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications…”
Genetics is now a subset of epigenetics, in which multiple dynamic molecules play key roles in homeostasis.
Any appeal to accidental processes to accomplish an unbelievable coincidence is really just an appeal to unbelievable coincidence.
This is one key issue on which proponents of ID and of theistic evolution differ.
“Nylon-eating bacteria? What the heck?” you say. “Why does this matter?”