When Obama endorsed legal gay marriage this week, he cited his daughters Sasha and Malia as factors in his evolving stance, noting that some of their friends have gay parents in admirably committed relationships. That was enough to provoke Bristol Palin, who fired off a blog post chiding Obama for being influenced by what "teenagers think after one too many episodes of Glee." Instead, she said, the president should have explained "to Malia and Sasha that, while [their] friends' parents are no doubt lovely people, that's not a reason to change thousands of years of thinking about marriage." This isn't the first time Bristol has written an open letter to Obama, nor is it the first time she's stirred up controversy. Here, a brief history of Palin's notable flaps:

Aug. 29, 2008
GOP presidential nominee John McCain names little-known Alaska Gov. Sarah Palin (R) as his running mate, introducing the world to the Palin family

Sept. 1, 2008
Sarah Palin announces that her daughter Bristol, 17, is pregnant, and will marry the father, Levi Johnston. "Democrats believe her having the baby is scandalous," says Cathy Beers at The National Ledger. "This will get ugly, and expect the attacks on Bristol to escalate."

February 16, 2009
In her first interview since giving birth, Bristol goes on Fox News and declares that the sort of abstinence policies promoted by her mother are simply "not realistic at all."

May 6, 2009
Bristol, now a pro-abstinence spokesperson for the Candie's Foundation, says on Good Morning America that "regardless of what I did personally, I just think that abstinence is the only... 100 percent foolproof way to prevent pregnancy." She insists that her February statement was taken out of context.

August 2010
After an on-again, off-again relationship, Palin and Johnston break up for good — still unmarried. This is like "the Wasilla version of The Hills," says Allahpundit at Hot Air.

Nov. 19, 2010
The TV contest Dancing With the Stars responds to accusations that Bristol, now a contestant on the show, has beat out other, more talented dancers thanks to an organized vote-rigging scheme fueled by fans of Sarah Palin. Baloney, says executive producer Conrad Green. "She deserves it." Jim Robinson, founder of right-wing website Freerepublic — which has hosted discussions with titles such as "make liberal heads explode and vote for Bristol" — is similarly skeptical about an organized conspiracy, telling People, "The Tea Party's not that organized."

Jan. 27, 2011
Washington University in St. Louis disinvites Bristol from a "Sex Week" panel discussion on abstinence. Students had objected to Palin's keynote speech and, especially, her proposed $20,000 fee. It's not like she brings a "unique and engaging perspective" to the topic, says Sean Janda at Student Life. "There are presumably thousands of individuals just in the St. Louis area [who] went through teenage pregnancies that have the exact same perspective that Ms. Palin does" — and could be hired to speak for considerably less money.

April 5, 2011
Tax documents show that, as an abstinence ambassador for the Candie's Foundation, Bristol earned $262,000 in 2010, while in the same period the foundation spent just $35,000 on grants to health and counseling clinics for pregnant teenagers. That means that "for every dollar Bristol gave to the cause, she gave $7.50 to herself," says E.D. Kain at Forbes. Of all the valuable things she's learned from her mom, "the most valuable lesson is how to milk her celebrity status for all its worth."

May 3, 2011
Bristol hits the red carpet at the Candie's Foundation benefit gala in New York, sporting a new look — or more specifically, a new face. Rumors abound that she had plastic surgery on her nose, chin, jaw, and cheeks. Palin responds that she had medically necessary "corrective jaw surgery" that, along with a liquid diet, incidentally "improved the way I look.... I don't obsess over my face."

June 24, 2011
Bristol's memoir, Not Afraid of Life, is released, with some sharp elbows thrown at the McCain family, especially daughter Meghan. Meghan McCain strikes back, leading to a "catfight so epic, it would make the New Jersey housewives blush," says MSNBC's Powerwall.

Sept. 22, 2011
Bristol Palin gets in a shouting match with a fellow patron at a West Hollywood watering hole. After Bristol falls off the mechanical bull she was riding, a man insults her and her mother, using crass language. Why don't you like my mom? Bristol shot back. "Is it because you're a homosexual and that's why you hate her?"

March 18, 2012
In an open letter to Obama on the website Patheos, Bristol says that since the president phoned Georgetown Law student Sandra Fluke after Rush Limbaugh called her a "slut," "I figured I might be next." After all, she says, "[Obama's] $1,000,000 donor Bill Maher" has said "reprehensible things about my family." Asking Obama to broadly condemn "all instances of sexism is reasonable," says Laura Donovan at The Jane Dough, but this is just silly. "The president doesn't have time to reach out to every girl who has ever had misogynistic terms hurled in her direction."

May 11, 2012
Bristol publishes her strange response to Obama's pro-gay marriage remarks. Besides accusing the president of basing his decision on Glee's powers of persuasion, Bristol slams Obama for failing to lead his family "in the right ways of thinking," adding "we know that in general, kids do better growing up in a mother/father home. Ideally, fathers help shape their kids' worldview." What does that say about Bristol, asks The Huffington Post. She's not only a single mother, but as she notes, "Levi is not part of the child's life."

Sources: ABCCNN (2), Forbes, Hot AirHuffington Post (2), The Jane Dough, Los Angeles Times, MSNBC, National LedgerPeople (2), Politico, Softpedia, St. Louis Today, Student Life, TMZ, Washington Post