The standard genetic code has sixty-four codons: four bases read in groups of three gives four cubed, which is sixty-four. The I Ching has sixty-four hexagrams: two line states in six positions gives two to the sixth, which is also sixty-four. The equality is exact and it has generated a substantial literature.
The equality is also empty. Four cubed and two to the sixth are the same quantity by necessity, since four is two squared: any system built from four symbols in triplets and any system built from two symbols in sextets must both give sixty-four. Nothing is being discovered when the two are found to match. The same relation holds between two-to-the-sixth and any other route to sixty-four, and it says nothing whatever about either system.
The comparison was made in passing by the molecular biologist Gunther Stent in 1969 and developed at length by Martin Schonberger in Verborgener Schlussel zum Leben in 1973, translated as The I Ching and the Genetic Code: The Hidden Key to Life. Schonberger proposed specific mappings between individual hexagrams and individual codons or amino acids. Those mappings are the part that would have to be tested, and they do not survive testing: the assignments are arbitrary, different authors following the same method produce different tables, and no assignment has been derived independently by anyone starting from the biology.
This is worth setting out precisely because the underlying facts are both true. The I Ching has sixty-four hexagrams. The genetic code has sixty-four codons. What does not follow is that the one anticipates the other, and a reader who knows the arithmetic will discount any source that presents the coincidence as significant.