i would like to thank u a lot aunty ji my situation was the very same my caught my brother who is 6 yrs younger to me watching porn a lot. i took the initiative of talking to him obviously he was ashamed and scared but some how he needed some support which i being an elder sister did told him what is right and wrong . we do talk about such stuff time to time, his friends belong to a society where having sex is a very day to day thing so in order to educate him properly i took the step. to all those who are reading this do take your initiative to teach your siblings or children to teach or they will get into wrong paths.