What is the ruling on belonging to a specific tribe when there is a doubt, not exceeding 10%, regarding the validity of the lineage, along with a blood match? Is it advisable to attribute oneself to an ancestor instead of a professional title? Is it obligatory to perform a DNA test to confirm lineage?

If your ancestors informed you that their origin is from the mentioned tribe, then there is no objection to affiliating yourself with it, because people are to be believed regarding their lineages. However, if you have not heard this from elders or trustworthy individuals, or if you do not trust what you have heard, then it is not permissible for you to affiliate yourself with it. You should remain with your current name or attribute yourself to your profession or craft. Islamic law does not see a necessity for using medical means to prove or deny lineage.