Be careful of typing
An Enneagram number is NOT Identity. Have you noticed that even after you have all the information about the types, in the sense of having the characteristics you can find in a dozen books, there are still some people you can't type? And sometimes, actually quite often, you can't type people you know quite well?
Part of the reason is that the list of character traits you find in the books are just that - traits. They are behaviors - that's all we can see directly. Your Enneagram style, or as I prefer to call it, your Enneagram strategy is about energy and motivation. To get at someone's motives requires inference from a variety of sources: repetition of certain things, predictability under stress, large patterns and intensity of some behaviors, not to mention body configurations and breathing patterns and other physical and mental attributes.
But there is another, more sinister problem. What are you looking at? If you are looking at a person with love and affection, you don't see the type first, you see the person. This person has a type, just like they have a skin color or ethnic origin, but if you love them, they aren't your focus. Remember those pictures that have a foreground/background option? If you look at you can see either the vase or the two profiles of faces? Or the old woman or the young one?
Those are examples of foreground/background choices. If you put the person in the foreground, then you related to them with all the nuance and complexity of a person. If, however, you become type-happy, you begin to look for their style, you may put that in the foreground and the person in the background. You say silly things to yourself like, "Well, she's a four, so I'll treat her this way," instead of saying, "I think Jane needs some time alone, or she needs company, or she needs whatever."
Helen Palmer has a fine book that could be dangerous, The Enneagram in Love and Work. In it, she tells just how each type is most apt to relate to any other type. For example, if a Three and a Five are working together and the Five is the boss, "here are the problems that may arise." Then she gets detailed, and her details are based on years of experience.
Here's the problem. Every Five is slightly different in age, gender, size, intelligence, ethnic background, socioeconomic class or a hundred other categories. Five style behavior is going to be modified by all those plus the level of health of the strategy. The great danger here is arrogance (not Palmer's, yours and mine). If we know all about being a Five, an implicit assumption can creep in that I know all about the person.
This is called using your Enneagram style as an identity. If you think this is abstract, let me point out that at the International Enneagram Conference in Chicago in July, (a fine conference, by the way), when people were issued the ID card, it included their Enneagram number. Sorry. Your Enneagram style is NOT your identity. It would be much more accurate to say it is the direction in which your identity is skewed.
Carolyn Myss (pronounced Mace) is a New Age darling. She was on the cover of both New Age Journal and Yoga Journal. She is a medical intuitive whose topic is "Why we don't heal." She argues that for many of us, our psychic wounds become our badge of belonging and our claim on other's attention/affection. She calls this identification and appreciation of our problems "woundology." It's a clumsy word, but if you've ever been introduced to someone and within five minutes you know they've lost their inner child, or been sexually abused, or love to watch the 700 Club or any other physical or spiritual aberration, you are in the presence of what we're talking about. It's one thing to introduce yourself at an AA meeting by saying, "I'm Tom and I'm an alcoholic," it's quite another to so identify with that problem that you start doing it at social or business meetings.
So typing is good clean fun when you know what you're doing, when you have a right to do it publicly and when you see the person first. For example, in a issue of Vanity Fair, Elizabeth Dole is profiled. It's a fine article and you can tell from the article that she is a 3 with a 2 wing. We have a right to observe these things in a public figure whose personality may affect us and the whole country. That's not all she is, it is, like her leadership talents, part of what we ought to know about a possible first lady. But it is one fact among many, it isn't her identity. Oprah Winfrey is a three, also and she certainly is different from "Liddy."
So to answer the question I began with, the reason it can often be really hard to type your parents or others close to you is that you love them and you see them as persons. You don't see them as types. They are so unique to you - and part of love is seeing how unique the person is. Every teenager justifies their crush by saying, "he or she is different." Mothers worry about what the difference might be, but it is a code word that means, "I see the uniqueness with the eyes of love."
There is one qualifier. If you are in love with someone and are having conflicts with that person, no matter how much you love them, their Enneagram style is apt to become annoyingly clear. And also may certainly be at the heart of your conflict. Of course, your own Enneagram style may emerge in a conflict, too.
So remember, our Enneagram style is what is wrong with us. Don't use it as an identity, either for yourself or others. You'll miss a lot.