Brother is watching porn on my laptop?

I have a laptop, and it's the only one that has a webcam in my house ( it is built in ). My brother watches endless porn on it. Porn, porn, and more porn. He even does live webcam shows on webcam sex sites. Like a C2C thing. The thing is, the computer is registered in MY name, and it has like the I.P. location and all that stuff. I sign up for a lot of college sites and I'm afraid somehow they will see the sites he goes on. He sometimes even goes on porn websites while im still logged into facebook, and does live webcam shows while I'm in skype. My father could care less. He thinks I'm a bit of a loser. We are also both 16 ( so the live webcam shows aren't getting better.... ) and we are both twins, so if HIS PICTURES END UP ON THE INTERNET... there's no proof if it was him or me. And he will surely blame it on me. What should I do? Can all these college sites see what kind of websites he goes on while he's on my laptop? Or is it safe to nothing will happen to me? I'm particularly worried cause once he left one of the live webcam shows on... I didn't know.... and I just got out of the shower, and was completely naked. This other dude saw me ( my brother is bi ) and well took pictures of me... i had to get my brother to explain to him that i am not my brother, and we are twins. He said he deleted them, but I doubt it. I feel really exposed. What's worse is the college sites and future employers seeing what he does and thinking it is me. I'm legitimately terrified for my future. Once again we are both only 16.