The typical person that is vulnerable to developing anorexia is perfectionistic and a people pleaser . They must have things just so and are often the mediators of the family. When problems come along, they often try hard to believe that they don't exist or they try hard to get the problem to go away as soon as possible. Often they care very much about what other people think of them, whether those people be their parents or their friends or even crushes. Caring so much about pleasing others and wanting to be liked usually ends up being the gateway to someone vulnerable developing anorexia.
Society puts control and money and thinness on the same pedestal, as well.
To be thin is to be in control and to be worthy of attention. The person susceptible to developing anorexia sees all of this very clearly and begins to dislike themselves. This is why the dislike towards themselves and the dieting doesn't stop and continues on to severe extremes. Besides society, there are obviously other factors that can trigger someone susceptible to developing a full-blown case of anorexia. Family is definitely one.