The answer to this is 1986. There was a time when people thought that Janet Jackson’s popularity was only because of her brother Michael but she was able to prove over time that she has her own style and her own fans. She and Michael handled rumors before stating that they were only the same person but they proved that the speculation was wrong when they appeared together on one stage.
The fact that she was able to make a lot of albums says a lot about her own strength as an artist. There were also a lot of people who are familiar with her different songs. You just have to say some of her song titles and people will recognize these titles immediately.