The feud between Britney Spears and her sister Jamie Lynn Spears keeps growing, now that the iconic sister claims the Nickelodeon actress should take a lie detector test.The 40-year-old artist posted a lengthy message sharing her thoughts on Jamie Lynn’s best seller book, declaring that the timing of her book release was “unbelievable,” refering to Britney’s new found freedom following the end of her 13-year conservatorship, in which she experienced difficult and traumatizing situations.Britney went on to accuse her sister of lying, posting a video from a recent episode of ‘The Real,’ where the hosts talked about the information in Jamie’s new memoir ‘Things I Should Have Said.’“National best seller ???? DUH…. the timing of your book was unbelievable Jamie Lynn … especially knowing the whole world had no clue what was really done to me !!!!” Britney continued, “My whole family including you is saying YOU DIDN’T KNOW ….