I'm guessing that won't help even if it becomes a reality. These days even proper paternity tests are useless if one end up on a birth certificate without his knowledge. You're still liable even if not guilty.
Edit: That being said... this naked faking app can cause of lot of problems in the workplace and home.
Yeah I think it's a great idea for a site/service much akin to the OP.
I imagine there would be a big draw just sticking in famous parents and kids to see if there is a match.
Edit: That being said... this naked faking app can cause of lot of problems in the workplace and home.