Is it normal for females to leave skid marks on panties , is it because when i get wet ??

no it is not my period or pee , ok let me explain , you know how all females have their own aroma vegina,,,, ok my question is why do i leave skid marks on my undies , is it normal?? it's not from period or pee is nothing like that! my sister gets it too , is it a female thing?????? come on dont act like you dont know what im taling about!!! please just answer my question.