Kate Middleton and Prince William want to expand their family. The royal couple has reportedly told friends they wanted three kids close in age to grow up together.

“They want at least three kids and for them to be close in age,” sources close to the couple told Vanity Fair. There are rumors among the royal couple’s friends that the Duke and Duchess of Cambridge will not wait too long before trying for another baby.

The couple is based in the Amner Hall country estate in Norfolk in the queen’s Sandringham Estate, and travel to their apartment in Kensington Palace in London for overnight stays and official engagements occasionally. After a childhood under the constant glare of cameras and paparazzi chasing him, his brother Prince Harry and their mother Princess Diana, William wants a simple childhood for his kids Prince George and Princess Charlotte.

“I’m concentrating very much on my role as a father. I’m a new father and I take my duties and my responsibilities to my family very seriously and I want to bring my children up as good people with the idea of service and duty to others as very important,” said William in an interview with BBC in April.

The 33-year-old royal added that if he is not able to give time to his kids, he would keep on worrying about their future. The Duke of Cambridge said this while addressing critics, refuting accusations and defending his decision to put his family first.

It came to light earlier this year that William carried out just 87 public appearances in the U.K. and 35 overseas in 2015, in contrast to his grandfather the Duke of Edinburgh, who had 217 engagements at home and 33 abroad last year. A royal source added that when it came to William’s family, “there is no negotiation.”