Biogenetic Medicine

In Technology's Promise, Halal speculates on a variety of potential future technological developments.  One area he discusses is biogenetic medicine.  The DNA mapping has already lead to the discovery of specific genetic markers for inheritable diseases.  Stem cell research holds the promise of potentially replacing diseased or damaged organs.  We can (and do) manipulate the DNA of crops to make them more hardy, pest-resistant, etc.  Bacteria and retro-viruses have been modified to offer methods of introducing specific DNA into a particular host organism.  Over time, DNA modification could be used to attempt to replace a specific genome sequence indicating high probability for breast cancer with a healthy sequence inserted at that point through some type of "infection" mechanism, so new cells would replicate with the healthy sequence rather than the unhealthy.  Such technological advances come with a host of ethical, moral, and environmental issues.  Aside from the basic "is it ethical to do this" questions, we also have a question of "is it advantageous to the planet as a whole to do this?"  If we prolong the lives of people on the planet now substantially and exponentially (by decades rather than the current incremental improvements in longevity) how do we ensure our population is sustainable with the resources at hand?  How do we modify and manage birth rates to keep from over-crowding our finite planetary options?  Or, do we need to explore similar growth in planetary expansion and settlement to avoid over-population and ecosystem destruction here on Earth?  Reaching further down this path, if we prolong life indefinitely, and restrict reproduction in order to remain sustainable, what do we give up in innovation and creativity?  If the next Einstein, Mozart, etc. is never born due to population controls, where do we get the next great innovation.  Do we run the risk of creating a stagnating society because fresh ideas and fresh energy do not come along every generation to replace our existing outdated thinking?

Curing sickness is good.  Prolonging life is good.  But I have to wonder, how do we know when too much of a good thing turns bad...