The Tremere

Mages in life, warlocks in undeath. House Tremere dwell in the occult and mastered the dark arts of magic. Tremere were originally a group of human mages from House Tremere of the Order of Hermes. When they found their magical life-extending elixirs started failing due to the growing lack of belief in magic, From the order of Hermes, many mortals who seek illumination found it in the cold world of darkness. As magic abandoned this earth the magi of the Order of Hermes experimented on kindred from clan Tzimisce to obtain immortality, and they succeeded by becoming kindred themselves. Since magic was no longer found in the world the Tremere found a powerful substitute in blood magic. The Tremere are one of the youngest vampire clans, having just come into existence during the Dark Ages. In the little time since then they made incredible inroads within vampiric society and are arguably the most powerful clan in the modern nights. This was due in no small part to their strict hierarchy, secretive nature, and mastery of Thaumaturgy, the clan's trademark discipline.

The Tremere have no natural curse like the rest of the clans, yet they are not without one. All  kindred of clan Tremere are 1 step to being blood bond. To be blood bonded is to drink the vitae of a cainite 3 times and to be subject of that cainites will. Here is an example of the power of being blood bonded to another kindred:

After the first sip of blood, the thrall begins to develop strong feelings for the regent, whether love or hate, though they are still free to act as they choose. Those in a one-drink bond may unconsciously seek out the regent, seemingly accidentally running into them on a frequent basis.
After the second sip, the regent becomes a very important person to the thrall, who may go out of their way to seek the regent's attention or please them. It becomes difficult for the thrall to do anything that would harm the regent, and the regent likewise finds it easier to convince the thrall of things. Though the thrall's craving for the regent's blood increases, they still retain their free-will.
After the third sip, the blood bond is complete. The thrall is now subject to the regent completely and loves them as much as they are capable of loving anyone. The regent is the most important person in the thrall's life and takes priority over all else; sufficiently weak-willed individuals will commit any act the regent asks of them.
A self inflicted curse perhaps, being blood bonded has a terrifying price, all kindred can be blood bonded and some are foolish enough to do it as a substitute for love, but the Tremere show such respect for their clan that they willingly come one step of being blood bonded to the seven elders of their clan. Not a curse of Cain but perhaps an even more powerful than any other kindred to have.