The earlier maturation in females may be a possible explanation for this disparity.
Environmental chemical exposure is one of the factors implicated in the recent downward trend of earlier sexual maturation.
Kittens can go flat any time during early maturation, some flattening as late as 10 days of age or (in very rare cases) later.
For girls early maturation can sometimes lead to increased self-consciousness, though a typical aspect in maturing females.
While early maturation may lead to problems for girls, among boys it appears to be a social advantage.
For example, the traits of sweet aroma and early maturation may breed true, while off- spring vary in size and shape.
Ditto "early maturation": those cute little girls that got their boobies way too soon.
Water temperature may play an important role in the earlier sexual maturation of captive specimens.
Can girls who are still emotionally and socially immature adjust well to early physical maturation?