The origin of defective genetic traits -- depends ( at least according to Morgan) -- on the total aspect of internal defections. What is inside and what is outside is what is at issue.
The history of biology has been a continual deflection from owning any and all defects. Given Morgan's separation of cacogenics and eugencis ("the defective materials ( cacogenics ) that have become incorporated in the species, rather with the discovery of superlative human materials, their preservation and perpetuation (eugenics)" one can easily understand that eugenics and biosteganography ( more on this another post) share a dynamic connect-ability. Thus when it comes to understanding the origin of those defective traits that the current economics of personalized medicine is attempting to realize a market around, one must take care to understand both the eugenical and biosteganographic implications of such an enterprise but to do so we must clearly understand what biophysical defects really are. To do so requires one to take a stand on how evolution works and role DNA plays.
Davenport (in 1902) established ( Faber - US Scientists Role in Eugenics) Cold Spring Harbor to create a ” Biological Experiment Station for the study of evolution” with an ‘aim’ to be the “analytic and experimental study of the causes of specific differentiation – of race change.” Pearson’s difference of organic and homotypic correlations in somatic tissues establishes the mathematical basis for discovering categories of specific differentiation but because Bateson and Pearson never were able to see eye to eye, the idea of race change relative to differentiation and difference never became differentiant individually and the maths of symmetrical affects remained overlaid on the individual organism dissections into individual traits under adaptation or not. This has allowed us to remain in the social situation we are in today. Eugenics thus is actually an idea that attempts to segregate and prevent reproduction of organic correlations into homotypes. We must attempt to understand biosteganography analogously if we are going to be clear how to medically distinguish an infection from a defection. Strange as it may seem there are still really simple things that need to be completely understood.
In the origin of life, raw materials were not transformed into DNA. DNA provides the reference coordinate system from which bifurcations necessary for nutrition and reproduction rest. These divisions may be electrical, chemical or mechanical but because RNA and DNA have different replication properties under an organon of reversalizations and complementations, separations forced by these different (proximate) means may be combined to contain an attraction-repulsion kinematics dynamically supporting life. The question never was, “What came before DNA?” but rather it is, “What came ‘above’ DNA?”
Organisms are never able to obtain free power during their evolution but only to convert energy into forms maintained but since protein molecular evolution may constrain the degree of functional reversibility through which commutivity and associativity remains active, biosteganography aside, total evolvability depends on a balancing of genic selection and whole genome phenetics. This dynamic permits a differentiant definition of cladistic symmetry and polyphyletic biophysics as disciplines through which the adaptive landscape balances these effects over time.
A lot more work is necessary before we can most fully understand the origin of genetic defects reflected across the generations and down lines of decent.