The eating disorders are complex illnesses with multiple predisposing factors.

Family transmission represents a major vulnerability factor for eating disorders. the exact mechanism by which this family history predisposes to eating disorders is unknown.

Several lines of evidence suggest genetic influence. the genetic factors definitely contribute, probably through multiple effects on temperament cognitive style personality, mood-regulating tendencies, set points for weight and predispositions toward physical activity. Studies have identified areas of particular interest on chromosomes 1, 2 and 13.

The influence of family functioning style as a potential predisposing factor remains controversial. Minuchin (1978) held that a specific pattern of relationships could be identified, consisting of enmeshment, over protectiveness, rigidity and lack of conflict resolution. Disturbed relationships are often found in families of patients with Anorexia Nervosa (AN).

The authors present a clinical series of 4 patients diagnosed with AN and with family history of the same disease: A 26-year-old female and sister, a 16-year-old female and mother, a 19-year-old female and mother and a 20-year-old male and cousin.

These patients are under treatment in an eating disorders unit of a psychiatric department.

This case series illustrates the familial association of AN, which is due to biological vulnerability (genetics) and psychosocial factors (family functioning style and family history of eating disorders).

Although no single predisposing factor is necessary or sufficient by itself to lead to an eating disorder, the likelihood that an eating disorder will occur seems to be related to the number and severity of predisposing risk factors.