I think the only "famous" people I'm related to might be horse thieves. I'm talking about the kind of DNA test that is offered at ancestry.com.
AncestryDNATM includes:
- Full breakdown of genetic ethnicity
- Dynamic list of potential new relatives updated in real-time
- Simple process to receive your personal results online within weeks
- Ability to integrate with Ancestry.com
- Test is for both men and women
Here's the faq they have online with more details
AncestryDNA Frequently Asked Questions