can't make new vampires, can see sunlight
Thin-blooded or duskborn, are terms primarily used to refer to Caitiff and vampires of the 14th, or higher, generations.
More objectively the term Thin-Blooded denotes a Cainite who is part of the Thin-Blood "clan" in 5th Edition or an individual who suffered from the Thin Blood Flaw, introduced in earlier editions (also known as Thin Blood Syndrome). That said, "thin-blooded" is a term that can also contain some amount of subjective interpretation. Blood "thickness" is a relative concept: Cainites of lower generations have more highly-concentrated or "thicker" Vitae, while those of higher generations are considered to have "thinner" Vitae.
For centuries, the thin-blooded have been persecuted by elders, Gehenna cults, and other Noddists that fear their existence because Gehenna prophecies seem to indicate thin-blooded vampires are a sign of the End Times. While in previous centuries the Caitiff bore the brunt of this hatred, the upsurge of 14th and 15th generation Kindred has become a matter of great debate and concern, and has notably resulted in the return of the office of the Scourge in Camarilla cities. In the Modern Nights, while only about half of 14th generation vampires are afflicted by the Thin-blood Syndrome, all 15th generation vampires are. Until recently, they were thought to be the final Generation, but evidently vampiric blood gradually thickens over the centuries. There are rumors that some vampires of the 16th Generation have begun to appear.
Thin-bloods are not allowed to join the Camarilla, and are branded with the mark of the crescent moon, to signify their lowly status.
Vampires with Thin Blood Syndrome possess exceptionally diluted vitae. This weakness however, manifests differently for each Thinblood, independant of generation, a 14th generation thin-blood may be too weak to even Blood Bond with a mortal, while a 15th might still retain the ability to Embrace, and vice versa. Among the dusk-born, the lines are blurred.
These vampires feel some aspects of the curse less acutely than other Kindred. They are less affected by sunlight, both physically and psychologically; they find it easier to wake during the day, and may survive exposure to dim sunlight unharmed, however many lack the natural resilience of vampires. They can hold down food for longer periods of time and even digest it as sustenance with a great deal of effort. Their bodies display some signs of true life; sometimes their hair or nails will grow, or they will feel the beat of their heart. A very small number have even fathered or, more rarely, given birth to children. Such offspring are known as dhampirs, and their nature is not well understood.Many thin-blooded vampires are unable to learn standard Disciplines, being forced to rely upon Alchemy in order to derive greater power from their blood. Through it, they are able to replicate disciplines up to a certain degree, as well as create effects not possible to do using normal Disciplines, perhaps with the exception of Blood Sorcery. The Duskborn are also greatly tied to the Resonance, gaining access to disciplines when drinking the resonance associated with it.The thin-blooded also share an oracular ability that is amplified within groups and grants them knowledge of the plots and deeds of Methuselahs and the Antediluvians. Naturally, this makes them of great interest to the few who know their secret, but debates rage over the source of their visions and whether they can be trusted. Some believe the visions are memories of things glimpsed during their longer than normal period between death and rebirth as a vampire, while others believe the thin-blooded are being used by the Antediluvians to mislead those who would fight them. Many Kindred simply want to destroy anyone who could learn their secrets through such gifts, though for their part the thin-blooded rarely understand the significance of what they see.Thin-bloods in Vampire: The Masquerade 5th Edition cannot usually learn Disciplines the normal way; instead they need to drink blood with a special resonance to get the ability to use one temporarily. Additionally thin-bloods are capable of learning Thin-Blood Alchemy to create formulae, counterfeiting normal Disciplines or creating whole new effects.