Lacey Schwartz comes from a long line of New York Jews whose ancestors immigrated to the United States from Eastern Europe. Raised in a white milieu, she had no reason to think she was anything but a caucasian. But with the disclosure that her biological father was an African American, she was thrown into an identity crisis.

Her journey of discovery unfolds in Little White Lie, an enveloping and moving documentary to be broadcast by PBS on Monday, March 23 at 10 p.m. (check local listings). Written, produced and directed by Schwartz, and told through home videos, archival footage and interviews, it’s about the importance of roots, the heartbreak of lies and the power of truth.

“I grew up believing I was white,” says Schwartz, who spent a comfortable childhood in Woodstock, New York, where few, if any, blacks lived. As she says in the first minute of the film, it never occurred to her that she was passing. Nor was she pretending to be someone else.

Schwartz, however, was different. As a relative recounts, she was born with a yellowish tint. And in nursery school, a classmate asked to examine her gums.

Schwartz had been told that her great-grandfather, a Moorish-looking man, was a Sicilian Italian. Schwartz accepted her mother’s lie at face value, but outsiders thought otherwise, assuming that she was an Ethiopian Jew, or had been adopted. Her non-biological Jewish father, Robert, had no desire to discuss the issue.

Matt, her biracial boyfriend, prompted Schwartz to question her lily white ancestry. Whatever doubts she may have had about her real racial background vanished after Georgetown University admitted her as a black student. She began attending black student social functions and, for the first time, she felt she really belonged.

Burning with curiosity, she asked her mother to come clean. Finally, she confessed, admitting she had had a long affair with a black man named Rodney Parker, who worked in the parks department. The news came as a relief to Schwartz. But to Robert, who had divorced Schwartz’s mother, the admission was painful, living proof that his wife had been unfaithful.

Shortly before Schwartz’s 30th birthday, Parker died. She attended his funeral, where it was announced that Schwartz was one of his daughters. There was no going back now. From that point forward, she considered herself a black woman. There is rich irony here. The name Schwartz means black in Yiddish.

Having internalized her dual identity, Schwartz hoped that a lifetime of lies — which had torn her family apart — could be supplanted by the truth and thereby contribute to the healing process.

Little White Lie leaves a viewer with the message that deceit and deception cannot stand the test of time in personal relationships.