This is a very poor post, full of almost comically bad arguments and rationalizations.
One way around this is to find some robust metric that most people would agree indicates guilt. One such measure, I believe, would be murder rate. If people in different cultures vary in the guilt they feel for committing murder, then this should hold them back and show up as a variation in the murder rate.
This borders on the idiotic. Since the author doesn't understand the obvious huge problem that it's impossible in this case to control for other factors, which are likely to be overwhelmingly important, none of their arguments should be taken seriously. It's the sort of cluelessness that makes it likely that in all other cases the author was merely fishing around for plausible correlations, rather than tried to judge the issue or build a convincing argument.
There is evidence that it [the distinction between modern and traditional] is caused by inbreeding and the accumulation of genes for familial altruism...
What evidence?
Since studies on this are non-existent as far as I know
Oh, OK.
– no doubt for political reasons
But political reasons didn't prevent people from publishing studies on race and gender and IQ, or the whole of evolutionary psychology from existing.
Really, the whole thing is very, very bad, and that even before they get to "gene variants for guilt proneness".
Related: The Psychological Diversity of Mankind, An African Folktale, many of the more interesting infanticide & abortion debates on this site
A fascinating post that however might need some background reading, most relevant material is linked in the article itself. I encourage reading up on the material.
Link to article.
Stories about changelings replacing babies and the recommended course of action being basically to expose the child is not a human universal, they are found only in European cultures. These rely more heavily on guilt and less on shame to regulate behavior than most other human societies. This may not be a coincidence. The stories look like they work as a ready made rationalization to reduce guilt from infanticide. Common problems often acquire common solutions like this.