9. The method of claim 8 , wherein the ID tokens are generated from e-mail addresses of the first and second individuals.
8. A method of controlling access to information of a first individual in response to a request for the information by a second individual and returning the information to the second individual based on the relationship between the first and second individuals, comprising the steps of: generating, at a local computer system that manages a first database, an ID token of the first individual and an ID token of the second individual from records stored in the first database using a one-way hash algorithm; transmitting a request for information about a relationship between the first and second individuals over a computer network from the local computer system to a third party computer system that manages a second database, the request including the ID tokens of the first and second individuals and identifying the one-way hash algorithm used to generate the ID tokens; receiving, at the local computer system, information about the relationship between the first and second individuals over the computer network from the third party computer system; and returning the information from the local computer system to the second individual based on the relationship between the first and second individuals.