I'm not really well-read into Somalia's clan system. However, it will be interesting to see if there was genetic differences between clans though. At like 30%+ difference. However, I would say Qabil is a social construct, not biological -- unless there is evidence. We all do speak the same language with different dialects, look similar and have the same culture. For the most part, from the outside (from subjective experience), we are mostly the same.
The interesting thing is Somali nationalism is new as I'm aware of unless history proofs me wrong.
I would not be surprised if a genetic analyses crushes the relationships of the subclans. It would not shock me if an ceyr for example is closer to me than an MJ. Darodists like at @Amun would lose it if turns out they are related to Sab more than other Darods.
It is my humble hypothesis that these clans go back to professions and trades people used to do, and with the penetration of Salafism and pan-Arabism in the peninsula for the last few centuries that these lineage myths were created.