Which of the following statements about adolescence is not correct?

Developmental psychology treats adolescence primarily as a socially constructed life-stage: puberty supplies a broadly universal biological trigger, but the length, meaning, and rites attached to this transition are shaped by each society's own customs, so the lived experience of adolescence differs from culture to culture rather than being uniform.

Checking each statement against this framework:

• Calling adolescence a social construction matches the standard account -- cultures assign their own meaning to this stage, so this statement is accurate.

• Marking its onset at puberty -- the biological process that brings sexual maturity and reproductive capacity -- is the conventional developmental marker, so this statement is accurate.

• Describing it as a transition spanning physical, cognitive, and psychosocial change is the standard multi-domain definition, so this statement is accurate.

• Claiming that children across different cultures usher in and experience adolescence in a similar manner contradicts the core idea that this stage is culturally shaped -- anthropological studies of coming-of-age practices show wide variation in duration, rites, and social expectations across societies, so this statement is the factually incorrect one.

Since three of the four statements align with the standard developmental account and only the claim of cross-cultural uniformity is contradicted by evidence, that is the statement the question is asking for -- the one that is not correct.