Barbara and Jenna Bush, 27, reflected on their years in the White House in an open letter to 10-year-old Malia Obama and her 7-year-old sister Sasha, in the Wall Street Journal on Tuesday.

"We also first saw the White House through the innocent, optimistic eyes of children," they wrote, acknowledging their seven-year-old perspectives when their grandfather George Bush was sworn in as the 41st president in 1989.

"Our seven-year-old imaginations soared as we played in the enormous, beautiful rooms; our dreams, our games, as romantic as her surroundings. At night, the house sang us quiet songs through the chimneys as we fell asleep."

The twins returned to the White House in 2001 after their father was elected 43rd president of the United States.

"The White House welcomed us back and there is no doubt that it is a magical place at any age," wrote Jenna, an author and school teacher, and Barbara, who has worked for various museums and charities.

The twins advised the Obama girls to "absorb it all, enjoy it all," as four years goes by fast. But they also gave more specific advice:

- surround yourself with loyal friends

- if you're travelling with your parents over Halloween, don't let it stop you from doing what you would normally do

- cherish your animals "because sometimes you'll need the quiet comfort that only animals can provide"

- slide down the banister of the solarium, go to T-ball games, have swimming parties, and play sardines on the White House lawn. Have fun and enjoy your childhood

- when your dad throws out the first pitch for the Yankees, go to the game

- in fact, go to anything and everything you possibly can

But they cautioned the Obama girls that life as the First Daughters would not always be easy with their father portrayed differently than they know him.

"Many people will think they know him, but they have no idea how he felt the day you were born, the pride he felt on your first day of school, or how much you both love being his daughters," they wrote.