Alien breeding protocol

Yes, i know, i know. Just let me get a word in!

OK, so we all know it's impossible and, as Carl Sagan said, it'd be easier to get a petunia to breed with a human than to produce Spock. Even so, genes are information and a code which is interpreted by a system leading to living organisms if there are no lethal alleles. We happen to have a code consisting of a system which converts sequences of adenine, cytosine, guanine and thiamine into sequences of amino acids which become peptides and so forth. Other codes on this planet exist too, for instance the presence of uracil in RNA and the variant bases used in some viruses. There are also other amino acids such as the ones containing selenium, which sort of have their own codons.

In fact, hypothetically there could be a completely different system which uses neither purines and pyrimidines nor amino acids yet still produces viable organisms with different biochemistry or maybe even organisms whose function is not dependent on the details of their biochemistry at all, for instance ones based on fullerenes which could be based on boron or silicon instead of carbon but be functionally the same, or on a more macro level, made of clockwork composed of steel or brass - the precise biochemistry is not crucial to their function.

Abstracting this further, look at every organism in functional terms, as a set of instructions for producing a system which responds to its environment, reproduces and the like, which form a kind of cybernetic diagram. Take this diagram and work out a set of translation rules so that whereas one organism concerned may in fact be, say, a Von Neumann probe which got out of hand and mutated, and the other is a slime mould, the respective "genomes" can be converted into each others' codes.

Flash forward to, i dunno, the twenty-second century and Amanda Grayson decides to make the beast with two backs with Sarek. She has the option of humungously good birth control, to the extent that thenadays, who would even bother to make luurve with a member of the same species if it's for fun rather than reproduction unless they were also the same sex and your species has more than one? However, she chooses Spock genesis instead. Just as by that time, the Federation has the universal translator (which wouldn't work of course), she now has recourse to a femidom which does the genetic code translation work for her. Clearly this is post-Singularity and the descendant of the warehouse-sized devices originally employed in the late twenty-first century where one sexual partner would plug themselves into one end in a room a few blocks away from the other and the factory would manufacture the appropriate gametes, but technology marches on and it fits in a membrane.

The barrier of species, previously considered as impermeable as the sound barrier or the inability to operate within the abdominal cavity, has been overcome as a result of evolution. The species concerned realised that the borders between them could be abolished to allow convenient free trade of genetic traits and looks back on the present protectionism as about as antiquated as the Corn Laws.

We don't see any of this in Star Trek or whatever because it's boring, but it's there - they just don't mention it because they take it for granted.