An old man walks into a lawyer's offices and announces that he wants a divorce.

"You're kidding!" says the lawyer. "You and Tilly have been married for 75 years.""I know that. Are you going to help me or am I going to have to get another lawyer?"

"I'll help," replies the lawyer, "but you've got to tell me why you're doing this now."

"We had to wait until the children were dead."

The joke is bittersweet and June Louin Tapp tells it that way with a trace of a smile on her face and a touch of pain in her voice.

With her own divorce four years ago, a surprise after 32 years of marriage, she came to realize just how much reality there was in the old joke.

She knew because she saw that her two daughters were emotionally upset by her divorce. That didn't seem right. Both daughters were in their early 20s and were intelligent, thoughtful individuals, seemingly old enough and mature enough to understand.

Louin Tapp, a professor in child development psychology at the University of Minnesota, checked what academic researchers had to say about her predicament with her adult children.

More than 2 million children under 18 are caught in parental divorce each year. It is unknown how many adults are involved in the mid-life divorce of their parents, but the National Center for Health Statistics reports that nearly 12 percent of all divorces in 1985 involved marriages of 20 years or longer.

She discovered numerous studies on the impact of divorce on young children and adolescents, but virtually nothing on its effect on grown children. So she decided to conduct her own study.

At first, she and her oldest daughter, Mara, talked about collaborating on the project. They quickly realized that wouldn't work. The divorce had exposed too many raw nerves for both of them and those raw nerves were causing flare-ups between mother and daughter.

Louin Tapp shifted gears. She got some of her students to help her interview individuals, ranging in age from 20 to 35, whose parents had divorced.

The results were surprising:

The adults reacted much the same as young children. They were hurt and angry, especially at not being told what was going on. And they felt insecure because they were caught in the middle between their warring parents.

Most were resentful toward the parent usually the father who had initiated the divorce. Only 12 percent believed both parents were equally responsible.

Half of those interviewed were married. They expressed anxiety and concern about their own marriages, although insisting they would try to avoid divorce themselves. Most said they'd try counseling or mediation before thinking of divorce.

Those who were single were "cautious" about eventually getting married. Half the single women said their dating patterns were affected.

Everyone was asked to list the "bad things" caused by the divorce. They mentioned "feelings of loneliness, anxiety about relations with their parents and a sense of loss of family." The sense of loss was exaggerated by the sale of the family home. Also listed were "discouragement about economic problems and the legal expenses related to the divorce."

Under "good things," they listed "the conflict is over" and that "parents now have freedom and can have their own lifestyles."

The hurt feelings and the depression were still present for those who had gone through the experience several years earlier.

Tapp found the reaction to the study as surprising as the results. "I presented a paper at a conference in Venezuela," she said, "and people in the audience came up to me later and started telling me about their own experiences. It was like I had opened a spigot. They were eager to tell someone who would understand just what they had gone through with their parents."

Tapp was then asked by a prominent Venezuelan talk show host to appear on his television program. "There obviously was a lot of interest in the subject even though Venezuela is a (Roman) Catholic country," she said.

Two divorce studies similar to hers are being done in Venezuela and another in Mexico, she noted. "Divorce, and the resulting consequences, are becoming a world-wide problem."