Mary & Fred RAISING ROYAL REBELS!

DANISH TEENS ARE TESTING BOUNDARIES AS THEY GROW UP

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As parents to four teenagers, King Frederik and Queen Mary are surely used to choosing their battles when it comes to setting boundaries. Lately, three of their kids, Prince Christian, 19, Princess Isabella, 18, and Princess Josephine, 14, have been pushing some unexpected buttons!

"Christian and Isabella have been enjoying the summer musical festival season in Denmark," our royal source says. "Plus, it looks like Christian is all wrapped up in his first public romance."

Meanwhile, it's Josephine's decision to move away from home, to attend boarding school that's really got Fred, 57, and Mary, 53, scratching their heads.

"Mary never imagined she and Fred would be virtual empty-nesters so soon," our source says. "She's hugging her youngest son Vincent extra hard right now."

Isabella THE PARTY PRINCESS