Now we are at the third order: splicing genes within a species.
Some of it is known, but the function of each of the thirty thousand genes has to be figured out one at a time.
Among more general works are Brequigny, Histoire des revolutions de Genes 'usqu'en 1748; Serra, La Storia dell' antica Liguria e di Genova (Turin, 1834) Varesi, Storia della repubblica di Genova sino al 1814 (Genoa, 18 351839); Canale, Storia dei Genovesi (Genoa, 1844-1854), Nuova istoria della repubblica di Genova (Florence, 1858), and Storia della rep. di Genova dall' anno 1528 al 1550 (Genoa, 1874); Blumenthal, Zur Verfassungsand Verwaltungsgeschichte Genua's im 12ten Jahrhundert (Kalbe an der Saalc, 1872); Mallison, Studies from Genoese History (London, 1875).
Finally, we get to the fourth order of GMO: being able to splice genes from one species into another species, a process known as transgenesis.
Whether this will be by growing working copies of the genes and administering them to a patient, by introducing a nanobot that fixes them, or by any of the dozen other methods currently being developed, I do not know.
In the fictitious case above, perhaps it turns out that these brown-eyed redheads who are stumbling through life and getting all banged up all have a certain protein deficiency caused by the same genes that make them redheaded and brown-eyed.
For example, a treatment for chronic myelogenous leukemia is based on an understanding that this cancer occurs when two particular genes fuse, go haywire (not the actual medical term), and order up a massive amount of white blood cells to be made.
From all of this, he developed the idea of dominant and recessive genes (although they weren't yet called that) and the mechanism for how traits are inherited.