The girl in this video has the mother doll care for the younger doll. which gender development theory/approach would best apply to her behavior?

I believe Evolutionary development approach would best apply to her behavior.

Evolutionary development approach views every development that happens in people's llife is made for increasing the chance of survival.

In this particular case, the mother tried to adjust the daughter so they have all the characteristic that currently in a tred for a certain type of gender in order to increase the chance of that girl being accepted by the rest of her social group in the future.