Actually, they aren't the same haircut.
About Mia
From Wikipedia:
Director Roman Polanski brought Vidal Sassoon to Hollywood from London in 1968, at a cost of $5,000 to create a unique pixie cut for Mia Farrow, who was to star in "Rosemary's Baby".
As for Twiggy
From Wikipedia:
In January 1966, young Lesley Hornby (later Twiggy) had her hair colored and cut short in London at Leonard of Mayfair, owned by celebrity hairdresser Leonard. The hair stylist was looking for models on whom to try out his new crop haircut, and he styled her hair in preparation for a few test head shots.
It is true that short, geometric cuts were exceptionally popular in that time period. Actually, we had so much fun with styles. My own was so long it was past my waist several inches. (I had an unpopular look anyway, being a redhead with very wavy hair. sigh) My sister had more of the Marlo Thomas/"That Girl" look. Twins in my sister's class in high school definitely were trying to capture the Twiggy/Carnaby Street look. FUN!
EDIT: I had to add my memory of how Mia went from very long hair to very short: Reportedly, she had a fight with Frank Sinatra. In anger, she chopped off her tresses! I still find that a mindboggling matchup: Sinatra 51 and Farrow 21! Well, they did last about two years.
Here's an interesting clip (no pun intended):
(W)hat are we without our dreams?
Making sure our fantasies
Do not overpower our realities. ~ RC

People tend to forget that Twiggy, a very popular model of the day, had this very same haircut. I still recall my sis buying her Barbie-like doll.

I agree!!! The haircut looked cute, she's a little pixie type girl and can wear that style!!! When she was healthy that is! It really did emphasize how sickly looking she was at first in her pregnancy!
IDK how true this is or not, maybe just celebrity gossip at the time. But I remember my My Mother telling me this when I was a little girl. That Mia and Frank Sinatra were dating, and apparently he loved her long blonde hair, and they got In a fight and she went and got a very short haircut to spite him!!!! Mia was on the soap Peyton Place, and my Mom said she had long hair and one day it was just cut really shockingly short, and the gossip at the time was what I just posted as to why she cut it!

In the book she does the same thing: after running around shopping and doing errands she then goes to Vidal Sassoon to get a chic haircut. Remember, as the wife of an up-and-coming-actor, one who put a lot of stock on appearances, living in a plush apartment and having all the right connections, getting an expensive haircut at a stylish salon was not unexpected of his wife. Also, the short hair cut, stylish thought it might have been, added immensely to her sick, emaciated look during her first months of pregnancy.

The haircut is also in the book. Some have suggested it's symbolically anti-lesbian propaganda to have a woman with short hair deliver the spawn of Satan because she is no longer a proper woman. I have no issue with this theory, but really haven't seen much evidence to back it up. _()_/
Short hair links:
http://www.imdb.com/board/10063522/board/thread/212245595?d=219961378#219961378
http://www.imdb.com/board/10063522/board/thread/212245595?d=221962339#221962339

She also had the heavy furniture put in front of the closet that led into Roman and Minnie's apartment to block them out. She was scared of them or didn't want anything to do with them or both.
When you get up in the morning, how do you decide what shade of black to wear? (Shallow Grave)

Thank you, thank you, thank you! I have dealt with this same issue with replies on "The Stepford Wives" by Ira Levin. Some people insist the wives were not killed, there were no robots, or they were only temporary, while the wives were brainwashed and one gal even thinks the wives were given boob jobs. Someone else argues that Joanna fought off the robot and pretended to be a robot after that. Sheesh. Some viewers seem to interpret these older movies based on current times. People look for things that are not there and are certainly not needed. Ira Levin is so amazing and I find it crazy that people want to think the plot varied so much from the original book. Yes the coven killed Mrs Gardenia. Yes the robots in Stepford Wives took the place of the real women.

I suspect you're trolling.
He is. I've seen him around.
Can't stop the signal.

I'm not trolling, and the book is beyond irrelevant when discussing this film, that is a fact.

I suspect you're trolling.
But either way, you're incorrect. Its clear the coven put the spell on Mrs. Gardenia, the same way they did to Hutch.
I'd say this cloud is Cumulo Nimbus.
Didn't he discover America?
Penfold, shush.

No it is not, it's a movie, I don't care if it's verbatim, the book is 1 billion % irrelevant. And I interpret it that way, there is nothing to say she was betrayed by the coven or something, maybe she was going senile.

Just because you interpret something a certain way, does not make it so.
Mrs. Gardenia had joined the Satanists but it scared her at some point, so she tried to leave. The coven did not like that, so they punished her.
And your sentence not only contradicts itself (proofreading before posting helps), but its incorrect.
The film is based on the novel, almost verbatim. So yes, the novel IS relevant.
I'd say this cloud is Cumulo Nimbus.
Didn't he discover America?
Penfold, shush.

I interpreted it like that because of association/disassociation, when people go crazy, etc, and you should bring book quotes into the discussion of the movie, they are not relevant.

The novel adds a sentence to the letter fragment.
Ro reads it on the desk:
.not the intriguing pastime I believed it to be. I can no longer associate myself..
Where did it ever say Mrs. Gardenia suffered form dementia??
The coven put her in a coma.
I'd say this cloud is Cumulo Nimbus.
Didn't he discover America?
Penfold, shush.

Damn.

This message has been deleted.

And more about Jews too.
Re: Why are so many female comics Jewish?
LetThemEatCake01
2 days ago (Thu Sep 17 2015 13:32:25)
Because being a jew is a fvking joke. It's not a nationality, it's not a culture, it's not an ethnicity, at the most it's a barbarian religion that should have been consigned to the history books, it's nothing. Being jewish is as substantial as me saying I'm a purple dot. They are the literal definition of a special snowflake. They are the same as every other beep in this world, but somehow they are different and unique because they are jewish, but what the fvk does that even mean? You can be latin, muslim, black, catholic, chinese, european, etc all of those are valid separate groups with their own identity, but what the fvk is it to be a jew?? You live in fvking new jersey, you don't have a religion, you are white, you are as much of an beep as anybody else but you're jewish?? What the fvk does that mean?
So I guess that answers your question, being a jew is a fvking joke.
http://www.imdb.com/board/22154960/board/nest/246379336?d=248424810#248424810
I'm so glad that IMDb allows us a chance to see who we're really dealing with.
I don't know if it's "really wacky," but your French is coming along.

beep off, I know more about films than you will ever do.

Why bother watching movies at all if you can't put two and two together on the simplest of levels?
I don't know if it's "really wacky," but your French is coming along.

I took that as a sign of dementia.

They find an unfinished note in the apartment that begins "I can no longer associate myself"
I don't know if it's "really wacky," but your French is coming along.

Where does it say that Gardenia no longer wanted to associate herself with them?

In the film, no real reason is given. You got the feeling she just wanted 'something different'.
Script-wise, it was likely to add to Ro's soon-to-be ill look.
In real life, it was Mia Farrow's real hair. She had cut it, much to the director's dismay, before filming began so she had to wear a wig for a while.
Yes, the Castavets put a curse on Mrs. Gardenia. Mrs. Gardenia had decided to not associate herself with the coven any more, and that apparently did not sit well with them. So they cursed her.
I'd say this cloud is Cumulo Nimbus.
Didn't he discover America?
Penfold, shush.