Salter wants to argue that co-ethnics (people of the same race as yourself) are to be considered kin - part of your extended family. The figure I heard was that a random pair of co-ethnics are related at about 1/128 (apparently this is third cousin relatedness). Based on Hamilton's theory of kin selection, Salter suggests that this should lead us to favour co-ethnics over those more distantly related ('other races'). *
There is more.
In a review of Salter's book (p.10) this is what Peter Gray (Department of Psychology, Boston College) had to say:
"Salter uses evolutionary theory not to explain behavior but to prescribe it. He clearly equates genetic interest with human good. In summing up his argument, in the “Afterword,” Salter writes, “My primary aim has not been to explain human behavior, but rather to offer social and political theory about what individuals should do if they want to behave adaptively” (p. 325, Salter’s italics). "Yes, it's usually pro-social doves banding together to protect themselves against hawks. Insofar as doves tend to achieve more civilization-wise, this has to be judged a good thing. And here I think is the crux of the argument. A civilised nation is better for all its members in terms of future survival (provided people actually get on and reproduce in the first place!). Looking around the world, and contra-Salter, a rational policy of genetic interests should be trying to boost alleles for intelligence, conscientiousness and general pro-sociality within our own societies. Strangely, that's exactly what immigration policies based on encouraging talent actually do.
"What we should do, according to Salter, is discriminate by race. We should do this because it is in our genetic interest to do so. Races differ genetically, and we share more genes with people of our own race than with those of different races, so it is in our genetic interest to favor our own race. To Salter, unlike to the rest of us who use evolutionary theory, genetic interest is not just the metaphorical “interest” of the gene, it is the real interest of the person. Salter writes, “Genetic interest residing in a population is a public good that belongs, as it were, to its individual members” (p. 43)."
"I’m sure that Salter is not in favor of rape. But his logic states clearly that it would be immoral to pass laws against rape if that behavior is in someone’s genetic interest. When you think of it, most of our laws — laws against rape, murder, stealing, exploitation, slavery, and the like — are interfering with someone’s ability to pursue their genetic interest."
* There is very little evidence of any built-in instinct which identifies somewhat genetically close kin. It seems very unlikely that we have spontaneous emotional connections to a random co-ethnic living in a town miles away. Even in a tight family environment, emotional bonding is apparently as much about growing up in close proximity as about cues from close genetic relatedness.