‘90s FAMILY : The Friend Trend : In the too-busy lives of today’s family, many parents try to make up for lost time by being something experts say they shouldn’t--pals to their kids.

Jenna invited her 16-year-old son to use her home for sex with his girlfriend, but eventually the sounds of her “baby’s” passion started grating on her.

“I thought, ‘Did I raise a rabbit?’ ” recalled the 36-year-old mother of one. But “better that than in some car or cheap motel. I know they’re going to do it. I’m not jumping with joy, but I figure if I’m open--if I’m my son’s friend--he’ll be open with me. I want to be able to protect my son.”

She’s also a friend to her son because her mother wasn’t one to her. “My mother was a tyrant,” she said. “A large, looming and distant figure. We spent all our time together fighting. I don’t want to ruin my quality time with (my son) fighting.”

Experts say reasons such as these are causing more adults who head the nation’s 36.1 million families with children to be friendly parents rather than disciplining elders.

“It’s now stylish to be a buddy with your child,” said Richard M. Eyre, co-author of “3 Steps to a Strong Family” (Simon & Schuster, 1994) and the bestseller “Teaching Your Children Values” (Simon & Schuster, 1993).

Of course, most parents want to get along with their children, Eyre acknowledged. An informal and gregarious relationship with a child is fine, even healthy, if it fosters respect and allows them to savor time together.

But such relationships become detrimental when parents feel reluctant to teach their children morals and manners or to devise--and enforce--family rules. “A lot of parents are afraid their children won’t like them if they discipline,” said Eyre, a Salt Lake City father of nine. “But in their hearts, they know the last thing a child needs or wants is a true friendship with a parent. It’s unfortunate, though, because I’m noticing parents aren’t listening to their hearts.”

Eyre and other experts attribute the friend trend to longer work hours by parents, meaning less supervision; an increase in single parents who are too overwhelmed to discipline, and more babies being raised by teen parents, with both generations needing discipline.

In Southern California, where the recession has lingered longer than in other regions, parents are at their friendliest, experts say. They often work 16-hour days at two part-time jobs. Or they may toil until exhaustion, hoping that they will not receive a pink slip after their company downsizes. All of which cuts away time with their children, explained Ellen Galinsky, co-president of the Families and Work Institute, a nonprofit research group in New York.

“(Parents) will slip into the just-friends technique because they feel guilty about being at work all the time,” said Galinsky, noting a 1993 institute study that found 66% of the 3,381 adults surveyed nationwide wanted more time with their children.

Less than a year ago, the study reflected Robert Hendricks’ struggle between work and family. The 37-year-old Inglewood resident said he devoted too much time to helping others as a minister and social worker and not enough time with his sons--Adam and Tyler, now 11 and 5.

“I would come home too tired to be a parent,” recalled Hendricks, who has since dropped his ministry job. “It was much easier to leave the disciplining up to Colleen and just be friends with my kids.”

“My kids saw me as the mean person and Robert as the fun teddy bear,” added Hendricks’ wife, Colleen, 36.

Hendricks has since experienced “a recent awakening.” His oldest, nearing adolescence, would smart-mouth his father, even after Hendricks repeatedly ordered him to quit.

“One day, I asked myself why I needed to be Adam’s friend. I recognize so strongly now that it’s because, as a child, I could never talk to my alcoholic father. I wanted so bad to tell him that I had been sexually abused, but I never could. I wanted to make sure my sons could tell me anything.”

He is now a disciplinarian. “As a social worker, I know that kids want discipline even if they don’t know it,” said Hendricks, who works at Long Beach Memorial Medical Center. “They need structure and stability. Otherwise, children will feel neglected and grow up with low self-esteem.”

They could grow up like Becca, a Northern California 13-year-old depicted in Peggy Orenstein’s “Schoolgirls: Young Women, Self-Esteem and the Confidence Gap,” to be published by Doubleday in September.

Becca’s mother treated her daughter like a best friend. She told Becca that she feared her husband--Becca’s father--and that sex with him was “like rape for her every night.” She told Becca her deepest secret: putting the child she had as a teen-ager up for adoption.

“It’s like we’re two eyes of a hurricane,” Becca told the author, explaining her relationship to her mother. (“Becca” is a pseudonym Orenstein created to ensure the girl’s privacy.)

“Becca’s mother inappropriately confided in her daughter, contributing to Becca’s low self-esteem,” said Orenstein, describing Becca’s distorted body image, erratic eating patterns and plummeting grades.

A 1993 study in the Journal of Research on Adolescence revealed that mothers are apt to confide in their daughters, like a friend, about family problems. Consequently, such a distressful divulgence makes daughters prone to depression.

American parents falsely believe that they can be complete friends with their children before age 18, said Yannick Sable, who observed family relationships when she lived in Africa and Europe. The single mother found parents in other countries almost always act as superiors to their children.

Those parents “guide children into maturity before being their true friend. This makes for a stronger (adult) friendship,” said Sable, 50, who shares a condo in Studio City with her 29-year-old daughter and 4-year-old granddaughter. “My daughter and I like living together as best friends.”

Maria Cancel, a 33-year-old mail carrier from Torrance, said she sometimes has to resist acting like a friend to Christina, the 9-year-old daughter she and her husband adopted two years ago.

“I want Christina to feel confident that I won’t beat or abandon her. And, of course, I want her to like us and her new home,” said Cancel, who also has a 17-year-old son. “But my main job is to care for (Christina) as a mother. I can’t be a friend to her when she’s this young.”

Christina giggled at the possibility. “Parents are supposed to be parents. Friends are younger than parents,” she explained. “But (parents) can be--they are--my favorite people in the whole world.”