Why does brothers aggravate sisters?
I assume the same reason brothers annoy brothers, or sisters annoy brothers, or sisters annoy sisters. The joy of making their life less enjoyable. Most people grow up, eventually.
because sisters annoy brothers.
Because Alex ^^ isn't smart
why do sisters aggravate brothers?
Why do sisters aggrivate brothers? Why do sisters aggrivate sisters? Why do brothers aggrivate brothers?
You have it backwards.