Prince William and Kate Middleton celebrate their anniversary as family of five

The royal couple marks seven years of marriage on Sunday — and they’ve got lots to celebrate. Prince William and Kate Middleton welcomed their third child — Prince Louis — on Monday, joining big brother Prince George and big sister Princess Charlotte into the royal family fold.

Now that they are back home in Kensington Palace with their new baby boy, Prince William and Kate Middleton have begun life as a family of five.

“It completes them,” royal biographer Ingrid Seward tells PEOPLE in this week’s cover story. A friend of the couple notes that Kate, 36, “is one of three siblings, and it’s a good family size. Boy-girl-boy is pretty cool as well.”

Parenthood, the friend adds, “suits them really well. They are enjoying it and are very happy.”

Seven years ago, Kate walked down the aisle of Westminster Abbey in her iconic Alexander McQueen gown to wed Prince William in a fairy tale wedding that was years in the making.  The glamorous couple, who met in college, tied the knot in a ceremony watched with the same sort of global interest as the prince’s parents, Prince Charles and the late Princess Diana, who wed in 1981.

A year-and-a-half after they wed, they announced the happy news that they were expecting their first child. Prince George was born in July 2013, and Princess Charlotte arrived two years later.

Big brother Prince George, 4, and big sister Princess Charlotte, who turns 3 on May 2, “are so excited,” says another friend. “Kate’s worried that Charlotte will feel it the hardest as the youngest, but she’s such a confident little girl and growing up so fast, Kate is hoping she will adjust.”

In Kate’s hometown of Bucklebury, “everyone around here is thrilled for them,” says a local. “It’s lovely that George and Charlotte have a little brother to play with, and Carole will be absolutely over the moon.”

With the new baby fifth in line for the throne, “hopefully, this little boy will be able to live a little outside the limelight,” says another Bucklebury villager. “We look forward to seeing him in the local park.”

This article originally appeared on PEOPLE.

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