Gus, Gus, GusGusGus...
That is not a "theory". It is merely conjecture.
Conjecture is useful only as a starting point in the scientific method. It isn't a scientific fact, a theory, or even a hypothesis (although it may be based on science), but is simply an idea thrown out for discussion. Conjecture, in the context of a set of valid observations, may lead to a hypothesis; and by testing that hypothesis sufficiently you might eventually develop a theory.
But calling the idea that all life came from another planet a theory is a grammar-school mistake.
Now, suggesting that four-stranded DNA might somehow be an improvement over existing two-stranded DNA isn't even conjecture. It's science fiction, very light on the "science" and heavy on the "fiction".
All forms of life on this planet, from the simplest protobacteria to the most complex vertebrate, contain more or less the same enzymes, subtrates, and cofactors needed to make RNA and DNA. Even primitive viral DNA is in essence no different than human DNA, which is why viruses can infect our bodies and make us sick.
Anyone who has survived a year of freshman chemistry and has then gone on to organic chemistry as a sophomore as prerequisites for beginning a study of biochemistry (in which the study of DNA begins) knows that the double-helix strands of a deoxyribonucleic acid (DNA) molecule form up in pair fashion for a bunch of reasons. For the same reason that RNA is always single-stranded, DNA is always double-stranded. To make a four-stranded nucleic acid chain, you would need to start with completely different chemical substrates, and a completely new set of enzymes to synthesize the various pieces and parts. DNA could never be four-stranded for these very well-understood chemical reasons, and if a four-stranded nucleic acid chain existed somewhere, it wouldn't be based on ribose or deoxyribose; it would have to be based on some completely different chemistry that does not exist, and never has existed, on planet Earth. Four-stranded nucleic acid chains are not something that will ever "evolve" on our planet, from species that live on this planet.
Thanks for provoking me to write this post. It's interesting to me on multiple levels.
Besides, it's giving me an excuse not to go out and clean the garage.
