By “the Diktat of Nature” we mean the fact that numerous qualities with which we came into the world were not qualities chosen by us. Through cosmetic measures or various forms of body culture, drugs or psychotherapies human beings revolt against the form of being that happens to have fallen respectively to their lot.
That which we recognize today to be a “genetic lottery” was cursed, as a “Diktat of Nature” already by Schiller in his Robbers: we are products of a game of dice initiated by our parents and will remain so until we have at our disposal some nativistic genetic technology thanks to which human beings who come to birth need no longer be ashamed of their own ugliness or other innate flaws and faults:
“I have every right to speak indignantly of Nature and by my honour I shall assert this right! For why was it not me that crawled first out of our mother’s womb? Why was I not the only child? And why did Nature impose on me this burden of ugliness?” (Schiller, The Robbers)
The character Franz in Schiller’s Robbers moralizes, here, the natural aspect of human being in such a way that he takes up a position in the debate on a liberal eugenics – long before any such debate actually takes place – and, in defence of human dignity, storms and rages against that “buffer of tradition” which Habermas, among others, was to see threatened only 200 years later.
In this cursing of Nature, however, no insight has yet been achieved into the fact that our existence, and our existence as the beings we are, are not to be traced back to some impersonal subject “Nature” but rather to the actions and omissions of parents.
 See Habermas, Die Zukunft der menschlichen Natur. Auf dem Weg zu einer liberalen Eugenik?