Britney Spears' family have been rocked by another scandal - pregnant teen Jamie Lynn's own birth was reportedly unplanned, and her father demanded a paternity test to make sure he was the baby's daddy.

As big sister Britney battles bipolar disorder and 16-year-old Jamie Lynn prepares to become a young mom, the girls' uncle has come forward with another past family secret. William Spears claims "history is repeating itself" - because Jamie Lynn wasn't planned.

The relative tells In Touch magazine that the young actress' father Jamie was concerned when his wife Lynne announced she was pregnant - because he had had a vasectomy after the couple's second child, Britney.

Uncle Willie says, "Jamie got awfully mad. He said it couldn't be his."

William Spears alleges his big brother then demanded a DNA test that proved he was the baby's biological father. He adds, "That's why they named her Jamie Lynn, to kind of make the point that she was from both of them."

The youngest Spears daughter stunned the world when she announced she was pregnant with boyfriend Casey Aldridge's child in December

-Jamie-Lynn Spears Pictures

(This news article provided by World Entertainment News Network)