This is from sims 1 through sims 3.

Some key points..

- The censors

- The Goth families

- Create a family

- Teens can't live alone

- Woohoo (or playing in bed) which is also censored

- Careers (not professions)

- School (where you can't see your sims)

- Deaths

- Ability to throw parties

So, I suspect all of these will be in ts4. What else? Post anything, including objects.

No teens in TS1 - just sayin'.

You could add 'having babies'

The Plumbob!

I disagree with the Goth family's consistency, though. Some things are consistent (e.g. Bella's red dress, the Goth manor, Cassandra's quirkiness) but the Gunther and Cornelia in the Sims 3 look nothing like their Sims 1 counterparts. In Old Town, Gunther is a dean and Cornelia is a member of the horticultural society. In Sunset Valley, they look like they'd rather be on an MTV reality show. Taking the "Goth" name a bit too literally, IMO.

If we count in-laws, Bella's brother Michael looked Asian/Latino in the Sims 1 with tan skin and black hair. In the Sims 3 he's white with red hair. Apparently, it's not just your aspiration that you can choose when you grow up, but your race as well!

The grim reaper, in all the sims games he has been there with his sythe. If he is not in sims 4 I will cry, he is my favourite NPC!

oh, i bet the reaper will definitely be back. forgot there's no teens in ts1. but pizza delivery will be back also.

Supernatural elements and magic, they have been every game at some point so far.

there's also the moodbar system.. although that's something that COULD be changed, i suspect, or replaced with something else.

The burglar. He/she looks the same in all the series.

Would have said hottubs, pool tables and pianos, but they decided to leave out all that stuff along with any other remotely fun objects in the basegame. Sims3 really was quite boring first, it didnt pick up untill the midnight expansion.

the Social Worker.

Maid service!

Peeing on the floor.

Sims. :P

Actually, parties aren't a consistent thing. They weren't added to TS1 until House Party.

One thing that is consistent, though, to paraphrase Medieval, Sims are dumb.

to get back at the first post, woohoo wasnt introduced right away in sims1. was added later with a specific bed that allowed it (and sims commented on it afterwards, one time the woman cheered and the man cried afterwards!)

Continence problems.

vacations
pets
Spinning around to change- unless it's different in Sims 3?
Pulling any object you can think out of their butt or Mary Poppins pockets!
dating scene.
ghosts.
A call reminding you that your Sim hasn't talked to another Sim for awhile.
Burglar's
relationship scores.

Llamas (they were in ts1, right?) and gnomes. The Sims has also always had a certain, somewhat grim, sense of humor, though that has declined a bit.

the bugs

the need for a lot of things to be fixed

paying bills
every empty residential lot has the mailbox and trashcan duo
telescopes (and incidences of alien abduction)
skill points

the suicidal fire dance.

the best dance ever put into the sims

Police
Vampires
Careers (law enforcement and criminal)

Route fail tantrums