It’s not grooming if they’re the same age—grooming is inherently rooted in a power differential due to age. For these two… it’s just growth being shaped by the people around you.
Definitely pseudo-scientific. The fact it’s based on different smell studies. People tended to like smells that were more dissimilar to their own than those that were similar, so family tended to dislike the smell of family more than strangers. This is hypothesized to be a mechanism to prevent...