While campaigning to be Alaska's governor she supported amending the state's constitution to ban same-sex marriage and continued to fight after it was legalised, pushing for continued support of the Defense of Marriage Act.
Neither Bristol nor her parents have commented publicly on the pending divorce, though the timing of her Instagram post drew notice. Todd filed for joint custody of Trig, since he's their only child who is under 18, according to court documents.
Sarah and Todd have four other children together.
The family was thrust into the spotlight when late Republican senator John McCain tapped Sarah Palin, then the governor of Alaska, as his running mate for the 2008 presidential election. The news was officially made public on Monday.
The defendant, presumably Sarah Palin, is asked to answer the complaint within 20 days.
See more on the Palin family in the video below. Sarah and Todd celebrated the Fourth of July separately in 2019, with Sarah spending it with daughter Bristol while Todd marked Independence Day with Trig, Piper and Willow.
Medred reported that the couple had been scheduled to appear together at a motorcycle rally in Sturgis, South Dakota, in early August, but Todd Palin was absent. Todd Palin competed on NBC's "Stars and Stripes" in 2012.
In 2010, the Palins were hit with $20 million divorce rumors, which they dismissed. After the election, she went on to sign several lucrative TV and publishing agreements and is reportedly worth $12 million, according to TMZ.