Her maiden name is Brenda Gail Webb; by marriage, she's Mrs. Vassilios Gatzimos. To country music fans who had heard of her at all, she was just the baby sister of the queen, Loretta Lynn. Then at the behest of big sister, she began to bill herself as Crystal Gayle. The inspiration came, Loretta confesses, from the Kristal hamburger chain (which is big in the Southern Rim)—"It's a real star name." "Yen," cracks kid sis, "but a star in what kind of show?"

As it turned out—respectable Grand Ole Opry. Crystal's I'll Get Over You just became the No. 1 country tune and appears to be rising on the overall pop charts higher than any single in the whole 16-year career of her Nashville purist sibling. But by any name, Crystal, now 25, would sing as sweet. Even before her first hit she began to tour with superstars, among them her sister's longtime pardner, Conway Twitty. This spring the Academy of Country Music picked Crystal as 1976's Most Promising Female Vocalist—an honor won the year before by Linda Ronstadt. (Of course, Loretta carried the night, copping four awards including Entertainer of the Year.)

"It's helped me and it's hurt me," says Crystal of her family connection. "It's never bothered me, though. I like having a sister as famous as Loretta." Notes Lynn, who previously and less successfully tried to boost another sister, Peggy Sue, and a brother, Jay Lee Webb: "If you help 'em, they feel guilty; if you don't help 'em, you feel guilty."

The two successful sisters are 16 years apart in age and grew up in two different worlds. Crystal, the eighth and last child in the family (and the only one to be born in a hospital), speaks with a decidedly different accent from Loretta, the second-eldest. Gayle has a Wabash, Ind., twang as compared to Lynn's pure Eastern Kentucky hills lilt. It was Loretta who was the troubled Coalminer's Daughter in song, life and now-new autobiography.

Loretta was only 13 when she met and married a local moonshiner, Oliver "Mooney" Lynn Jr., and was a grandmother at 29. But Crystal managed to restrain herself until she reached 20, when she wed Vassilios ("You can see why I'm called Bill"). Her high school swain, he was then a sophomore at the University of Indiana. For the past three years he's been managing Crystal's career, but this fall he enters Vanderbilt Law School. Right now the couple lives modestly for an aspiring queen of country music and prince regent. They have a small older house outside Nashville, situated on five acres, where they keep a horse and a dog "of every breed." Their movie tastes are relatively sophisticated—Woody Allen and Gene Wilder—though, somehow, they've missed Nashville, whose breakdown-prone heroine is patterned partially after sister Loretta.

Crystal herself grew up in Paintsville, Ky. She recalls, "Loretta was already married and out of the house. By the time I was aware of anything, she was already singing. I grew up singing to the records of Lesley Gore and Brenda Lee and folk music like Peter, Paul and Mary." When the coal mines were depleted, Crystal's father uprooted the family and moved them to a colony of ex-miners in Wabash. He was ailing with black lung and high blood pressure, so Crystal's mother supported them with a series of jobs, including nurse's aide work in a home for retarded children (until her recent retirement)."She was the backbone of the family," Crystal remembers, "and she still is, though I remember little things about Daddy, like his going to the store to get me Oreo cookies." (He died in 1959.) While still in school, Crystal appeared at fairs and jubilees and during summer vacations went on tour with Loretta, "which is really how we got to know each other. I'd do two songs in a typical kid act."

Then, in 1970, Loretta wrote a song for Brenda Lee, I've Cried the Blue Right Out of My Eyes. "But Brenda's eyes are brown," Crystal pointedly observes, "so I got it." That property was Crystal's breakthrough, a surprise country hit, and it emboldened her to make her own kind of music. "Country is what I'm in," she says. "I don't ever want to put it down, but I'd also like a fuller sound and to appeal to more people." Crystal, who does not at this point compose her own songs, calls Dolly Parton her favorite, not necessarily a put-down of her sibling. Although Loretta lives just 70 miles away in her own town, Hurricane Mills, and though Crystal hasn't visited in five years, they do occasionally cross paths on tour or in Nashville.

What next for Crystal Gayle? Perhaps the expected new $200,000 country-star custom van and an unexpected change in billing. "I don't like it much," says the former Brenda Gail Webb Gatzimos. "I may go back to my real name fairly soon."