Creating breeds of humans using incest, the way we do with animals

What if I were to tell you that I wanted to create an entirely new breed of horse, a strong, intelligent and beautiful breed with very unique physical and mental characteristic. Now of course, if I want to collect and hone a group of traits into one bloodline, that would necessarily mean I would need to use incest, as we do in all animal breeding programs. Now you know I am a responsible breeder and will make sure that I breed the horses in a direction which is healthy and I would be careful to weed out all diseases, and in the modern age I could use embryo screening to make sure I only have healthy embryos. Would you think I was crazy? No, you would think I was engaging in animal breeding and you would have no concern about the destiny of my breed which I promise will be stellar. 

However, as soon as we suggest this same process in humans all of a sudden people have a problem. Most people don't understand that incest does not CREAT disease. Some diseases are genetic and recessive at that. If a family has a negative recessive gene it is more likely to run in the family than outside the family. Thus it increases the rate of the chance of the child inheriting two copies of the defective gene from both parents. If there are no negative recessive genes in the family then there is no chance of the child becoming diseased simply because they were born of incest. And in today's world with genetic testing and embryo screening we could make sure that only embryos who do not have copies of the negative recessive gene are brought to term. This not to mention that the statistical rate of inheriting two copies of a negative recessive in incest is very low, less than 3% for first cousins, and with careful breeding and screening this can be brought to zero. 

This is how you would start the process of breeding thoroughbred subtypes of humans. There are traits that run in family lines, personalities and physical appearances, strengths and weaknesses. If we used incest we could hone these traits into creating a breed with certain characteristics. Now the issue is getting the population into incest, but this might be easier than you would think. We know that many many more people are attracted to incest than who would admit it under the current social climate, however we also know that privately there is a mass proliferation of incest porn and chat rooms which a brimming with disciples. All we need to do is legalize and destigmatize this institution and it will begin to proliferate. We can use natural fetishes to institute these breeding programs. 

As for the reason why you would want to do this, there are so many traits in humans that if amplified could make seriously unique and powerful people with aligned physical, mental, spiritual and emotional traits that they would raise them far above the averagely bred human. These new breeds of humans could then be bred together to create new breeds of unique humans who would help society with their honed abilities and proclivities. I could go more in to depth on this, but hopefully you get the point.