It's not exactly sibling rivalry, but it's close.
Sixteen-year-old Abby Sunderland of Thousand Oaks plans to set sail this week on what could be a record-setting voyage around the world.
If the name sounds familiar, it's because Abby's brother Zac sailed around the world last year.
He was 17 at the time and became the youngest person ever to complete the voyage solo.
Abby plans to do things a little differently.
She wants to sail "non-stop" around the globe. She also plans to take a more dangerous route.
Family members are concerned. but Abby is determined, and plans to set sail from Marina Del Rey later this week.