I have an older half sister that was given up for adoption about 10 years before I was born. I am 20 and she would be about 30. We have the same father. How do I go about looking for her? I do not know her name or date of birth. I do know my fathers name and her mothers name.

You actually have no rights when it comes to an adopted sibling.

You really only have a couple of things you can do:

1. Hire a private detective.
2. Register on reunion websites.