I think this can answer your question. I haven't had a case yet, let me know if I can assist after you look this over:

http://www.familytreedna.com/faq/answers.aspx?id=41#1615

NOTE: You or your test subject MUST be a male Lincoln in order to participate in the Lincoln DNA project. Since the results are all based on the Y-chromosome, which is only passed down through paternal lines to males, you or your subject must be a male of Lincoln name or biology.