Why Such a Big Deal About the Big 5?
But what about the psychological, personality impact of culture, socioeconomic class, etc., of origin on the significance of birth order or probability of having any siblings, e.g., in societies heavily biased toward having, favoring, pampering or "spoiling" males as firstborns or onlyborns—even to the extent of practicing female infanticide?
More importantly, are we to equate absence of an impact of birth order on the "Big 5" personality factors of extraversion, emotional stability, agreeableness, conscientiousness, or imagination with absence of an impact on anything directly or indirectly related to (including correlated with) personality?