From our initial analysis of the sequence of the human genome, particularly with the much smaller than expected number of human genes, the genetic determinists seemed to have clearly suffered a setback. After all, those looking for one gene for each human trait and disease couldn't possibly be accommodated with as few as twenty-odd thousand genes when hundreds of thousands were anticipated. Deciphering the genetic basis of human behavior has been a complex and largely unsatisfying endeavor due to the limitations of the existing tools of genetic trait analysis particularly with complex traits involving multiple genes.
All this will soon undergo a revolutionary transformation. The rate of change of DNA sequencing technology is continuing at an exponential pace. We are approaching the time when we will go from having a few human genome sequences to complex databases containing first tens, to hundreds of thousands, of complete genomes, then millions. Within a decade we will begin rapidly accumulating the complete genetic code of humans along with the phenotypic repertoire of the same individuals. By performing multifactorial analysis of the DNA sequence variations, together with the comprehensive phenotypic information gleaned from every branch of human investigatory discipline, for the first time in history, we will be able to provide answers to quantitatively questions of what is genetic versus what is due to the environment. This is already taking place in cancer research where we can measure the differences in genetic mutations inherited from our parents versus those acquired over our lives from environmental damage. This good news will help transform the treatment of cancer by allowing us to know which proteins need to be targeted.
However, when these new powerful computers and databases are used to help us analyze who we are as humans, will society at large, largely ignorant and afraid of science, be ready for the answers we are likely to get?
For example, we know from experiments on fruit flies that there are genes that control many behaviors, including sexual activity. We sequenced the dog genome a couple of years ago and now an additional breed has had its genome decoded. The canine world offers a unique look into the genetic basis of behavior. The large number of distinct dog breeds originated from the wolf genome by selective breeding, yet each breed retains only subsets of the wolf behavior spectrum. We know that there is a genetic basis not only of the appearance of the breeds with 30-fold difference in weight and 6-fold in height but in their inherited actions. For example border collies can use the power of their stare to herd sheep instead of freezing them in place prior to devouring them.
We attribute behaviors in other mammalian species to genes and genetics but when it comes to humans we seem to like the notion that we are all created equal, or that each child is a "blank slate". As we obtain the sequences of more and more mammalian genomes including more human sequences, together with basic observations and some common sense, we will be forced to turn away from the politically correct interpretations, as our new genomic tool sets provide the means to allow us to begin to sort out the reality about nature or nurture. In other words, we are at the threshold of a realistic biology of humankind.
It will inevitably be revealed that there are strong genetic components associated with most aspects of what we attribute to human existence including personality subtypes, language capabilities, mechanical abilities, intelligence, sexual activities and preferences, intuitive thinking, quality of memory, will power, temperament, athletic abilities, etc. We will find unique manifestations of human activity linked to genetics associated with isolated and/or inbred populations.
The danger rests with what we already know: that we are not all created equal. Further danger comes with our ability to quantify and measure the genetic side of the equation before we can fully understand the much more difficult task of evaluating environmental components of human existence. The genetic determinists will appear to be winning again, but we cannot let them forget the range of potential of human achievement with our limiting genetic repertoire.