Although Loretta Lynn was already married and living in her own home when younger sister Crystal Gayle (real name: Brenda Gail Webb) was born, the two were still especially close, People reported. In fact, Gayle would often spend her summers on tour with Lynn. And at age 16, she was called on to replace her sister at the Grand Ole Opry after Lynn had fallen sick.

It didn't take long for Gayle to decide that she wanted to follow in her big sister's footsteps and launch a music career, and Lynn was more than happy to help. She came up with her younger sibling's stage name and gave her some sound guidance. "She got me my first recording contract [in 1970], and she told me the best advice: 'Don't sing anything that I would because we're only going to be compared,'" Gayle told People. "She was right."

Lynn even wrote a song that became one of Gayle's best-known tunes, although the track — "I've Cried (the Blue Right Out of My Eyes)" — was originally intended for singer Brenda Lee. "Lee's eyes are brown, so I got it," Gayle explained.