How does the gender of siblings influence a person’s development?
Children learn a great deal by observing role models and imitating them. There are theories in developmental psychology that explain this; Albert Bandura, for example, has described it.
When parents or siblings display certain behaviours, this has an influence on the child. If this behaviour is gender-stereotypical, then it does indeed have an influence.
One might ask how gender-typical behaviour develops. Of course, there are certain biological predispositions. You can see in very young infants that ‘boys’ do things differently from ‘girls’. In this early phase, there are a few innate elements that are also linked to hormones such as testosterone. But later on, behaviour is strongly shaped by social factors.
In order to question stereotypes and role models, the individual needs a well-established sense of self. Only then are they able to question certain behaviours and certain perceptions held by others. This only happens during adolescence, sometime between the ages of 10 and 20.
Ultimately, within a family, the individual is influenced by the entire family structure. And thus also by older siblings.
Jenni, Oskar. 2021. Understanding Child Development. Practical knowledge about stages and disorders. Berlin.