By Peter Grier, Christian Science Monitor

Today is Barbara Bush’s birthday. It’s a milestone birthday too – “the big nine oh,” as her husband George would probably put it.

There’s going to be a blow-out celebration at the Bush clan retreat in Kennebunkport, Maine, of course, but it’s not just for Bush family members. Mrs. Bush is using the occasion to raise money for her signature issue, literacy. Over the years the Barbara Bush Foundation for Family Literacy has raised more than $40 million to promote reading among young children and parents whose literacy could use a boost.

As part of this birthday charity effort Mrs. Bush is lending her name to a $7 million challenge from the X Prize organization and Dollar General Literacy Foundation. This pot of money is a reward meant to prod software developers to create mobile apps to help improve adult reading skills.

That’s why it costs $5,000 for a single ticket to tonight’s Barbara Bush dinner. Or, if you’d rather give $100,000 or more, you can get six tickets to the dinner, two tickets to a private reception, and photo opportunity at the actual Bush home on Walker’s Point, six invitations to a second, casual meal, and a bunch of other stuff. Oh, and a round of golf on the day of the party, according to a piece in Politico last month.

There won’t be any jumping out of airplanes, however. That’s what ex-President George H.W. Bush did to celebrate his 90th, but his wife has no interest in that, reported her granddaughter Jenna Bush Hager on NBC’s “Today Show.”

And nobody pushes Barbara Bush into doing something she’s not interested in. To the contrary – she’s the Bush clan enforcer, as well as its matriarch.

How’d she earn the “enforcer” designation? “If you do something bad, I point it out to you,” she told Ms. Hager.

The American people have long approved of this kind of bluntness. Most first ladies are well-liked, according to polls, but Barbara Bush has a good claim on the title of most-popular modern presidential spouse.

Last year, for instance, she tied with Hillary Clinton in an NBC/Wall Street Journal survey for the title of “Most Admired First Lady of the last 25 Years”. Bush and Mrs. Clinton were both the choice of 27 percent of respondents.

And a 2014 Gallup poll showed her as a clear favorite. Seventy-seven percent of Americans had a favorable view of her, and only 10 percent had an unfavorable view, for a net rating of 67 percent. In this survey Hillary Clinton had a 56 to 37 split, for a net rating of 19, and daughter-in-law Laura Bush had a 73 to 15, for a net of 58.

Perhaps this proves that it’s not that bad for a US public figure to be acerbic. In Time Magazine, Mrs. Bush this week shares the best political advice she’s ever received.

“Be yourself. Well, maybe somebody a little nicer,” she told reporter Michael Duffy.