That was good feedback, thanks.
One can conclude that living apart from, or scarcely interacting with, a sibling during certain periods of childhood renders his or her influence moot.
Also, sisters probably influence each other much more than brothers do, as they are more likely to discuss clothing and shop together, even into adulthood.
To the extent that brothers influence, it probably often is limited to discussing dress codes (what to wear for an interview), if a father isn't doing that. Anecdotally, if boys are very close in age or appearance (like twins), some conscious choices to look different can arise. There too is influence from hand-me-downs, which were more common decades ago when books about clothing studies were being published. Back then, it was suggested that younger siblings are more interested in clothes.