As a guy, you're in your sister's room and she undresses to have her bath. I've been in this situation with my elder sister a number of time (even after she got married.) Each time I tell her its wrong, she just waves it aside. Who is wrong here?
Then, I often wonder why NORMAL men (like me) are not aroused in this kind of situation and get aroused even they see any other nude girl even on screen. Can medics/pyschologists educate us?

Mod, stop tampering with my words now. A-r-o-u-s-e-d changed to excited; un-d-r-e-s-s to uncloth. Kilode?

For me personaly, i dont think there's any things wronged with it. Countles times i've seen my sista naked and aware she is of it. But the intereresting parts of it is that i dont get horney seein her nayked, but exteremely horney seeing other's girl.

Religiously wrong when both of u re matured!!!

To me, it's nothing!!!!

bamto: As a guy, you're in your sister's room and she undresses to have her bath. I've been in this situation with my elder sister a number of time (even after she got married.) Each time I tell her its wrong, she just waves it aside. Who is wrong here?

Then, I often wonder why NORMAL men (like me) are not aroused in this kind of situation and get aroused even they see any other nude girl even on screen. Can medics/pyschologists educate us?

It is wrong, two words are key here: Privacy and Decency.

These two words should ensure that you avoid such situations even if there is a trend to see it as "normal".

Its wrong, what is bad is bad.