I suspect the reason Google wants your real name is to match it with credit headers. And before anyone calls me a tin-foiler please read the following and understand that I work in the industry. I'm not making a judgment call one way or the other as to whether this is "right" or not.
For those that don't know a credit header is information in a credit report that gives identifying information about a person. Credit headers contain:
Name, AKA's, Maiden Name, Date of Birth, Social Security Number and Issuing State, Relatives, along with Current and Previous Addresses which can go back 25+ years.
Credit headers have been ruled as to NOT be part of a credit report:
http://epic.org/privacy/fcra/
<blockquote>A credit header is identifying information from a credit report. It includes name, mother's maiden name, date of birth, sex, address, prior addresses, telephone number, and the Social Security Number.
Credit headers came into use after the FTC changed its definition of a credit report in the course of settling a case against TRW (now Experian). The FTC allowed the CRAs to treat headers as "above the line" information and to sell it with no legal protections for the individual. The reasoning was that this information did not relate to credit, and thus should not be considered part of the credit report.
Credit headers are used for location of individuals and for target marketing. They are sold in bulk by the CRAs and can be purchased online.</blockquote>
Google can simply take your IP address, trace it back and then run your name against the header database to locate individuals in your area with that name. The more unique your name the easier you are to identify. If you have a common name it would be further cross-referenced with other information like relative names or maiden names. Once identified they have your complete life history.