WEDNESDAY, July 18, 2018 (HealthDay News) -- Young adults raised by lesbian moms show the same mental well-being as those who grew up with heterosexual parents, a new study suggests.

The findings, published in the July 19 issue of the New England Journal of Medicine, come from the largest, longest-running study to track development of kids in "planned lesbian families."

The study has been following the same group of moms and offspring (conceived through donor insemination) since the 1980s. Over the years, the study has found that those kids are faring as well as -- or even better than -- other U.S. kids their age.

These latest findings show that's still true in young adulthood, a time when mental health conditions like depression or anxiety disorders often emerge, said lead researcher Dr. Nanette Gartrell.

"They're psychologically very healthy, even during this vulnerable time of life," said Gartrell, a visiting scholar at the Williams Institute at the University of California, Los Angeles School of Law.

The study began in 1986 with 84 families -- mostly headed by lesbian couples, but with some single lesbian moms, too. Back then, Gartrell said, many people assumed that kids of same-sex couples would not fare well.

"We were just coming out of a time period when homosexuality was considered a mental disorder," Gartrell said. "There were people arguing that homosexual parents could not be good parents."

But Gartrell's team has found that the reality does not match the stereotypes. One set of findings, published in 2010, showed that at age 17, kids of lesbian moms had fewer behavioral problems, versus the norm for U.S. teens. They were also doing better in school, based on their mothers' reports.

Beyond that, Gartrell said, none of the teens said they'd ever been physically or sexually abused by a parent or other caretaker -- far different from the norm for U.S. teenagers.

That finding, Gartrell said, counters the common myth that homosexual parents are more likely to abuse their children.

According to Dr. Jack Drescher, a clinical professor of psychiatry at Columbia University in New York City, "Research shows us that what's important for kids is that they have parents who love them -- and not whether their parents are straight or gay."