Lynne Spears is bewildered with the amount of interest in her daughters Britney and Jamie-Lynn - because they are just normal, homely girls.

The Toxic hitmaker has enjoyed an enormously successful singing career, and her younger sister rose to fame starring in teen show Zoey 101.

Both girls have become mothers, with Britney having two boys - Sean Preston, three, and Jayden James, two - with ex-husband Kevin Federline, while Jamie-Lynn welcomed tot Maddie with fiance Casey Aldridge earlier this year.

And despite watching their fame grow, their mother and her friends are shocked - because they still see them as the little girls they saw grow up.

She tells U.K. show Gmtv, "My friends and I talk about it and they go, 'What is the deal? What's so interesting about Britney? What is the deal with your daughters? I don't get it''

"People that have known us all our lives, they're mystified. They go, 'What is the deal?'"