There are 16 Starfield traits you choose from currently. You can only have three, and each gives you a permanent buff of sorts, usually with a downside to think about or a specific use to balance out. For example, the Neon Street Rat trait give you better mission rewards but only in the city of Neon. Spaced, on the other hand, gives you more health in space, but less on a planet's surface.
Traits are different from the basic Starfield skills you unlock and level up or receive as when you pick a Starfield background and starting skills. They seem to be a permanent choices currently, that you carry through out the game. Although there might be a respec ability yet to be revealed that will let you change them later. However the system works, Starfield traits will have a significant and specific impact on your adventuring so let's take a look at what we know about Starfield, what options are available and what Traits do.
All Starfield traits we know about so far

Right now there are sixteen separate Starfield traits we know about, with greater details revealed for a few in particular. To start with, here's the full list of Starfield traits that we currently know about:
- Alien DNA
- Empath
- Extrovert
- Freestar Collective Settler
- Introvert
- Kid Stuff
- Neon Street Rat
- Raised Enlightened
- Raised Universal
- Serpent's Embrace
- Spaced
- Starter Home
- Taskmaster
- Terra Firma
- United Colonies Native
- Unwanted Hero

Of course, no background is prevented from building and piloting their own giant spaceship. Find out about Starfield ship customization here!
Clearly this is a fairly extensive suite of personal histories and effect to choose from already, even if there aren't more to add to the list later down the line. Most if not all seem to be based around a fundamental personality or origin before the game starts, suggesting you're doing your own thing for a while before you head out into space. The UI revealed in the footage suggested that there were even more options available so there is likley more to play with, and it'll be interesting to see what the full mix of pros and cons will let you do.
For example, will you be able to mix and match elements as you choose you three three to balance out any negatives? Or will these really let you mix max a build around some hyper specific play styles. A lot of what we've seen suggests not, given the mix of good and bad, not to mention the there are some that are mutually exclusive. But gamers are nothing if not creative, so if there are any exploits to be found we'll no doubt hear about it within hours of launch.
Starfield traits and effects explained
Below we've listed the current effects of all the Starfield traits we've seen revealed in greater detail. Each trait effectively offers positive and negative effects and are chosen at character creation, having lasting impacts that are clearly meant to tweak the entire playthrough.
Players have to pick three at that point, though it's not yet been revealed if there'll be the chance to earn more during gameplay (though considering these features have been in previous Bethesda games, it seems likely). We'll be sure to expand this as more details emerge and we approach launch day!
Introvert

- Pros: Greater endurance when adventuring alone
- Cons: Less endurance when adventuring with other humans
- Notes: Can't be combined with Extrovert trait
Kid Stuff

- Pros: You can visit your parents at their home (exact benefits unknown)
- Cons: 10% of all money you earn is automatically sent to parents
Neon Street Rat

- Pros: Special dialogue options and better rewards from certain missions from Neon
- Cons: Crime bounty by other factions is greatly increased
- Notes: This is a Faction Allegiance trait, and cannot be combined with another Faction Allegiance trait
Raised Enlightened

- Pros: Significant discount at Enlightened organisation store
- Cons: Lose access to Sanctum Universum store
- Notes: This is a Religion trait, and cannot be combined with another Religion trait
Raised Universal

- Pros: Significant discount at Sanctum Universum store
- Cons: Lose access to Enlightened store
- Notes: This is a Religion trait, and cannot be combined with another Religion trait
Serpent's Embrace

- Pros: Grav jumping provides a boost to health and endurance
- Cons: Health and endurance are lowered if you don't grav jump regularly.
- Notes: This is a Religion trait, and cannot be combined with another Religion trait
Spaced

- Pros: Health and endurance are increased when in space
- Cons: Health and endurance are lowered when on the surface
- Notes: Can't be combined with Terra Firma trait
Starter Home

- Pros: You start with a small house on a "peaceful little moon"
- Cons: You have a 50,000 credit mortgage with GalBank (exact payment methods and penalties unknown)
