this picture of his father from 1965 to this picture showing cart as a boy with his dad in 1972. but had to be this. there is no other way around it. no mutual friends. reporter: cart says so far he has been able to communicate with his half brother on facebook but plans to get in touch with him as soon as he can. that is all the excitement. i really am looking forward to finding out more about my brother. reporter: intended or not, facebook continues to connect people from the past. some people think that is creepy being able to recognize faces like that. as handy and amazing in that story. there is still a downside. to do the auto tagging. right now, technology continues to evolve. very interesting. facebook face recognition is used to suggest friends for photo tagging not set up to introduce you to new people. it s really just to recognize the friends you already have. make it more convenient.