Questions on genetic engineering

Scientists have recently been able to genetically engineer chickens to render them unable to transmit avian flu.

This all sounds good for the poultry industry, but it brings to mind a few questions about genetic engineering, to which I certainly don't have any good answers.

What are the ethical implications of human beings trying to genetically change a creature with a central nervous system, whether genetically engineering chickens to avoid avian flu, or engineering pigs to synthesise omega-3 rather than omega-6 fatty acids thus providing healthier pork?

Would the ethics of the situation be different if these genetic changes were done with the goal of providing a better life for the birds/pigs themselves, rather than the goal of more profit to the people that were doing the genetic engineering?

What about the evolutionary side?  Genetic traits evolve over time.  Is human beings' interference with other species' genetics changing the course of evolution, or is our ability to do this simply a product of evolution and thus completely natural?

Suppose a family member had an incurable disease such as chronic leukemia or diabetes.  If this individual's parents had, before birth, chosen to have their offspring's genes engineered so that this disease would not have been able to happen (if the technology were available), would this be a different case to genetic engineering in chickens or pigs?  Would there be anything wrong with that?

In the chickens or pigs, nobody could ever explain to the chicken or pig what had happened nor why.  But in the would-have-been chronically ill person, presumably the child would grow up and understand that his parents had done something helpful for him.  The parents would have effectively provided the consent for medical treatment (genetic modification) on behalf of the child.  So effectively, there would be consent within the family.  For chickens and pigs, there's not even consent within the species.


As an afterthought:  could this ever lead to genetically engineering groups of people to fill certain roles in society?  Pre-programming the genes of, say, non-university educated groups, to be really good at farming so that they could crank out productive 14 hour-days on a farm every day?  And genetically engineering another group to be really good at truck-driving?  And another group to be really good at politics?  As though selectively breeding a certain type of dog or horse to accentuate a trait associated with that variety of animal, this would be genetically programming people to accentuate traits associated with different roles in society.  Humans trained in genetic engineering would become the ruling class and ultimately control the function of all other groups of people.  I'd hate to see what would happen.

http://www.sciencemag.org/content/331/6014/132.1.full?sid=5b36e31e-5329-41e4-927d-6e8a266bc6f3