Cursing past: A new biography reveals that ten-year-old Michelle Obama swore like a trooper . As first lady of the United States she can be nothing but the epitome of grace, elegance and politeness as she mingles with world leaders and celebrities at the White House and further afield. But it was not always so for Michelle Obama, who as a child was so foul-mouthed she lost out on an award at summer camp aged 10, according to a new biography. The first lady-to-be was an avid attendee at a day camp on the shores of Lake Michigan, and stood out as the most capable in her age group. But camp leaders were so taken aback by her salty tongue that they denied her a prestigious award when the camp ended, according to biographer Peter Slevin, whose Michelle Obama: A Life was previewed by People magazine. Michelle Robinson, as she was then known, as so stunned by the revelation that she changed her ways immediately and put an end to her 'cursing phase'. The anecdote surfaced in the upcoming book on Mrs Obama, which also includes the revelation that her mother was anxious about her marriage to future president Barack Obama – because he is mixed race rather than completely black. Slevin quotes her as saying: 'I was going through my cursing stage.' 'I didn't realize until my camp counselor at the end came up and said: "You know, you would have been best camper in your age group, but you curse so much".' 'And I thought I was being cool.' Mrs. Obama used to attend the camp regularly with her brother, Craig. She would have been ten years old at the camp held in 1974, while Craig would have been 11. Revelation: The anecdote about the young Michelle Obama (pictured right aged seven), emerged in the upcoming biography Michelle Obama: A Life by Peter Slevin, due out April 7 . Politeness incarnate: The first lady has since scrubbed up on her manners significantly. She is pictured above greeting Bun Rany, the wife of Cambodian Prime Minister Hun Sen . Carolina Herrera Carnation Floral Twill Silk Dress . Buy from Neiman Marcus here! Visit site . Another day, another fantastic sartorial choice from Michelle Obama. The First Lady is a woman who knows her own style that's for sure. She favors voluminous shapes adorned with bright prints. Just like this stunning Carolina Herrera dress. Michelle's fit and flare frock features a beautiful carnation floral-print twill, a bateau neckline and a pintucked center front. It's feminine and so very flattering. Carolina Herrera are known for their classic and elegant creations that make the ultimate statement. If you're looking to invest in a luxurious wow piece this new season then why not click right to Neiman Marcus now where you can still get Michelle's exact dress? It'll be your go-to piece for all your most fabulous summer soirees this year. We've also included some similar looks for less below which will have your new season style blooming in an instant... Kate Spade New York dress at Zappos . Visit site . Clove print dress at Nordstrom . Visit site . Christin Michaels dress at 6PM . Visit site . ECI floral print dress at Nordstrom . Visit site . The story about her once-foul mouth has emerged before: In 2013 she recounted the story to a group of reporters while promoting her anti-obesity campaign. It was then she revealed that the development stopped her swearing ways dead in their tracks, never to return. The first lady is currently giving her hard-won politeness an outing on the world stage, touring Asia to promote girls' education. She arrived in Cambodia Friday, where she spent time with the prime minister's wife and met high school students and education experts.
First lady-to-be was snubbed for award at summer camp by Lake Michigan . Said she was in her 'cursing phase' during episode in 1974 . Changed her ways when camp bosses told her swearing lost her the prize . Tidbit from Mrs. Obama's past was revealed in upcoming biography .