Loss of a parent as a child, or frequent separation from parents, "has a broad impact on adult personality," especially in large families, a study in the American Journal of Psychiatry concludes.

The long-term effects can include "frustration, anxiety, depression and withdrawal," and in some cases intermittent separation -- such as when a father is often away on business -- has the most profound impact.

Drs. Alan D. Sklar and Robert F. Harris performed personality tests on 247 men aged 18 to 25, all members of an Army battalion. Scores on the Minnesota Multiphasic Personality Inventory (MMPI) were significantly higher in certain categories -- including depression and introversion -- among those who were separated from a parent on a regular basis.

On the average, such a person "experienced approximately 500 separations from his father in the course of 18 years of life," they write. "This experience may leave the individual feeling uncertain about whether his father will be there when needed, helpless about the possibility of influencing his environment, and emotionally numb to loss and reunion."

The effects were greatest in large families, when parents had less time for each child. "A child in a small family might escape these effects," they write, "by turning more frequently to the mother or to other siblings for emotional support."