Sisters hate/love

I want my question is answered by GIRLS OLNY

girls who have sister ... do you feel some hate/love feeling to your sister ?

for exaplme want to fight your sister with bare bodies ...

hate : fight
Love : sex

explain me !

a real girl said to me : I have a recurring fantasy of fighting my sister

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girls ... i asked this question to know more about that

please explain me ... if its not normal why ?
i need your help

thats bad fetish i know ... but i need to hear more explains