Still applies here in my opinion. This family you know had 33% fewer biological children than they could have had. That means their DNA will be ever so slightl

Still applies here in my opinion. This family you know had 33% fewer biological children than they could have had. That means their DNA will be ever so slightly overwhelmed by families with the same desire and capacity for children who chose to have 100% biological offspring. Having said that, there certainly is some debate on whether genes are actually greater than memes when it comes to this kind of psychology. It could be that the human brain is general enough to be loaded with this kind of DNA self terminating software (meme) such that it continues for longer than you might otherwise expect, because the unrelated offspring still inherit the memes that motivated the decision to not prioritize your own genetically related offspring. However, given enough time and generations, there should still emerge a mutant human brain that is more immune to these kinds of memes, and that genetic lineage slowly out competes the one that is more accepting of raising unrelated offspring.