It's not that hard to imagine a rational argument where humans have evolved to grow with one or two parents, leading to all sorts of psychological prewiring.
(I'm not supporting the argument, just saying that it's not hard to come up with a plausible rational one)
To what extent? for example, imagine they still had identifiable parents with some some prominent role. I could also see the argument that parental role is diminished in modern society with the outsourcing to public schools.
The earliest evidence for nuclear families is in Germany, going back 3,000+ BCE [1]. We next seem it gain prominence in 13th-century England [2]. Otherwise, the default for non-nomadic societies was kin (extended family) or community oriented childrearing. Similar to what we see in traditional family structures in South America, Southern Europe and Asia.
> could also see the argument that parental role is diminished in modern society with the outsourcing to public schools
It would be difficult to make this argument given the primacy of parents in public schooling compared with e.g. their diminished role in kin- or community-based childrearing systems.
(I'm not supporting the argument, just saying that it's not hard to come up with a plausible rational one)