A more precise accounting is required.
We are all aware of Haldane’s oft-quoted assertion that he would lay down his life for two brothers or eight cousins, the genetic payoff of such altruistic self-sacrifice being the equivalence – as measured by ”bean-bag” genetics – of the numbers of gene copies between these sets of relatives.
In general, I am in broad agreement with the sentiment, although as we shall see, it requires modification. Even more broadly, those on the Far Right invoke this paradigm to support the idea of altruistic self-sacrifice in favor of larger numbers of an ethny, in defense if ethnic genetic interests. Likewise, I support that as well, with the proper modifications as with the smaller-scale examples of familial relatives.
Even though at first glance, Haldane’s reasoning seems sound, likely most people would be hesitant to follow that advice. In large part, this is the natural impulse of self-preservation, but there are other reasonable objections that can be made.
One could argue, all else being equal, that judging between two sets of equivalent genetics, it’s better to preserve yourself for reasons of control. A person concerned enough with genetic continuity that they would consider such altruistic self-sacrifice is someone likely to start a family, care for children, and properly actualize the continuity. Can you be sure your two brothers would do the same? Why are they in the position that they need your sacrifice to begin with? Are they stupid? Reckless? Are you sure they’ll act in support of your (in this case indirect) genetic continuity with the same vigor you would do for yourself? So, to be safe, maybe you need to raise the bar for self-sacrifice to three brothers or ten cousins?
A more important reason, and one that may be intuitively sensed by most people even though they wouldn’t be able to explain it, or likely even articulate their feeling about it, is that there is more about kinship than mere numbers of gene copies. Genetic structure is important – what genes are coinherited and, to the layman’s eye, what phenotypic traits (derived from those genes) are inherited together. Of course, family is going to be more similar here than (co-ethnic) strangers, but similarity is not identity. Even with siblings (apart from identical twins, which are a special case), recombination and independent assortment will ensure that your brothers will have a distinct genetic stricture from you. Now, granted, these same processed, even with a co-ethnic mate, will ensure that your children will also have a different genetic structure than you, but, all else being equal, your brothers’ children will be more unlike you, with respect to genetic structure, than your own children, as the “starting point” (you vs. your brothers) is already different. So, when genetic structure is taken into account, two brothers are not really your genetic equivalent. Apart from an identical twin, you have no genetic equivalent, just degrees of relative similarity and difference, even after numbers of gene copies are accounted for. Then how many brothers are sufficient for self-sacrifice? This requires a more rigorous analysis, which will be dependent upon accurate measures of genetic structure, and that’s not something we can expect SJW population geneticists are likely to do. However, while the overall Haldane argument – and its Salterian extension – makes sense the numbers given based on “bean bag” genetics is going to be an underestimation of where you need to draw the line in sacrificing yourself for others. On the other hand, the reverse is true – if you have to choose between your brothers and strangers, or between co-ethnics and non-ethnics, taking genetic structure into account means that helping your brothers and your co-ethnics is even more important than before, because in comparison to more genetically alien peoples, genetic structure amplifies how much more close you are to your brothers and your co-ethnics. It’s a double-edged sword: it makes your own preservation a bit more important, but it also makes the preservation of those more similar to you more important than those more distant.
Now, one can argue that after several generations of recombination and independent assortment – even assuming endogamous mating within the ethny – genetic structures derived from your posterity and those of your brothers will be more or less the same, converging on the common pool of ethny-specific genetic structures. So, while in the first generation, your offspring and that of your brothers may be distinct with respect to genetic structure, that difference would be attenuated over time and, as long as endogamous mating is maintained, your posterity and theirs would reflect similar genetic structures. But there are problems here. First, a rigorous analysis is required; perhaps some differences would continue over at least several generations; even if these differences are small, they nevertheless would need to be accounted for. Second, if it is true that familial genetic strictures would tend, over time, to converge on more generalized ethny-specific structures, then why bother favoring two brothers over two random co-ethnics? The brothers would share more of your genes, yes, and be more similar as far as genetic structure, but if one invokes “long term intergenerational effects” with respect to questioning the need to account for structure in modifying Haldane’s argument, then one can use the same “intergenerational effect” to directly question Haldane’s original premise. The answer I believe is that one must do the best they can at a given time in maximizing their genetic payoff, and hope that subsequent generations do the same. In the absence of the required analysis, one can simply argue that looking to the next generation, differences in genetic structure are important and, hence, two brothers are not quite the genetic equivalence of yourself. Your structure is different from theirs and the genetic payoff of your reproduction is greater for your than both of theirs combined. So, maybe you need to hold out and sacrifice for three (or more) brothers instead, including for the other reason outlined above. Note that these fine points deal with very close genetic similarity. When we are talking about racially alien peoples, the genetic distance becomes even more amplified with genetic structure, and in the absence of panmixia, ethny-specific patterns of genetic structure are broadly stable over evolutionary time (we can see that the Iceman is genetically more similar to Europeans than to, say, Asians of Africans, as one example).
In the absence of the sort of careful quantitative analysis that population geneticists won’t do, from a qualitative standpoint, it would be prudent to require more of a genetic payoff before engaging in Haldane-style altruistic self-sacrifice. On the other hand, when considering a choice in investing between two genetic entities, picking the group genetically closer to you is even more important when considering genetic structure. So, when the choice is between self vs. family or family vs. ethny, genetic structure will require a larger genetic payoff before agreeing to sacrifice the interests of the former for the latter. However, when considering a relative choice between ethny one vs. ethny two, genetic structure means that choosing the more similar-to-you ethny is even more important than with “bean-bag” genetics.
The overall Salterian imperative remains the same as before, once these adjustments are made.