I was following you until the end. > "Why are boys not being taught to be conscientious?" seems like a more fruitful question than "how can we make parents be

I was following you until the end. > "Why are boys not being taught to be conscientious?" seems like a more fruitful question than "how can we make parents be meaner to girls?" Woah now, hang on just a bit. I think you made a bit of a leap there. Let's recall that the authors reported a "slight" preference and a "small" effect. One thing that could explain this is simply how girls mature at a faster rate in childhood and adolescence. After all, the authors report, "Results showed that when favoritism was based on autonomy and control, parents tended to favor older siblings." If you control for age, then I'd expect sex-related differences in maturity to become more pronounced.