Dude's sister thinks he has the perfect penis.....not saying nefarity occurred, but if it didn't, it got real close.
It's not that uncommon for Indian sisters to give their bros handjobs while exposing their breasts (particularly the lower class and village people). I've seen a video of that (I was doing "research"

). There are also sex stories of Indian sisters giving blowjobs to their bros but preventing them from banging them coz they are afraid of a pregnancy and also probably coz they draw the line there. But no video proof of that, to my knowledge and I'm not about to go searching for that (I've better things to do). Anyway, before the nice Indian fellows here get furious at me, I'm NOT saying this is the norm and I've seen only one video of that. Based on my knowledge, it wouldn't surprise me if an Indian sis knew what her bro's penis looked like.
And this is not just an Indian thing. Ethiopian (and maybe other African cultures) women don't mind changing in front of their bros and popping out their breasts in front of them. In the Netherlands, family members are used to seeing each other naked, especially in the morning when they are trying to share a washroom to get ready for school/work etc.