It's a really good question, PTC. And one lots of people wonder about and try to deal with. So, let's give it some thought here.
SuperEgg's image of the different kinds of cookies is right on- we all have the right to show up in the world as whatever kind of cookie we are/want to be. And truth is, there's room for millions and millions of types of cookies in the world (all you have to do to see that is go online and put "cookies" into google! you'll see an almost infinite number of them come up).
It's also true that people have a variety of comfort levels with variety of cookies. At one end of the continuum are families that are way into all kinds, and easily accept into the fold any type that comes along. On the other end of the continuum are families that has a very specific image of "what a cookie should look like." And then, there is everything in between, in terms of being flexible about including/accepting a variety of cookie types.
Many, many of you guys that ended up with eating disorders and/or related things (as well as people who have ended up with all kinds of other difficulties- since being accepted as our own cookie type is CRUCIAL to healthy human/animal development) come from families/environments that are at the rigid/difficulty accepting a variety of cookie-types end of the continuum (as opposed to being somewhere in the middle- moderate). Families/environments where EDs develop tend to have rigid images of what people should be like, and this leads to you guys trying to make your cookie into exactly what you believe it "needs" or "should" be, instead of getting to simply hang out as whatever cookie type you happen to inherently be.
Here's a way we can work on a piece of this. I get how easy it is to say "I have to be perfect for (whoever)." The word sums up so many things and captures the feeling of how we believe we have to be in those relationships. Instead of leaving it at the "I have to be perfect" statement though, I've found it's helpful to try to be specific about what we mean when we say we have to be perfect. What being perfect means changes according to what relationship you are talking about at the moment.
For instance, I work with a young woman who lives with her family. This family is moderate in a political sense, they're not into physical appearance (parents couldn't care less if their daughter had the body shape of a kangaroo as long as she was healthy and happy about her body), and they don't have strict rules for things like curfews. They are, however, very rigid about they're religious beliefs. The daughter wants to explore religions; she's sure she is religious, but isn't sure exactly how that looks for her. She thinks she probably will end up in the same religion as her folks because that faith makes a lot of sense to her, but she wants to have the freedom to explore. In her family, being the perfect cookie requires her to have exactly the same faith and level of faith her parents have, and to not have questions about that faith.
In another family I work with religion isn't a controversial issue at all. Everyone shares the same beliefs and no one has any opposition to anyone exploring religions. In this family though, physical appearance and "social etiquette" are everything. Everyone, including the parents, looks like something out of a Barbie ad. In this family, the "right kind of cookie" to be is "blond, tall, thin, and artificial looking, and to act deferential and always polite in public."
And in yet another family, political affiliation determines whether the children are "behaving properly" in the world. No one is "allowed" to have differing political thoughts or beliefs (or even questions about differing beliefs or thoughts).
You can see that each family has different ideas of what constitutes a kid "behaving perfectly." It's important and helpful to be specific about how this manifests in your particular family or environment (and remember, I love families and this isn't AT ALL about blaming- it's about understanding how we have been shaped by our environment so we can make choices about what works and what we'd like to change. My experience is that parents in families where there is rigidity of one kind or another aren't having any fun either! They are often trapped in beliefs they don't even realize they have, or don't realize they have any choice about continuing with or changing).
In general, it's not every single thing that environments "require" us to be perfect about. It's a few, carefully selected things, "chosen" based on a family's or environment's or culture's values (or the values they think they should have!). As we get clearer about which things it is in each of our environments/families we can begin to make decisions about what to do with this information... remember, Step A, then Step B... let's do Step A first- what is real. This little project could be done as a list :) "Ways my family/environment thinks I should be"