Reese Witherspoon cried "tears of joy" when her niece graduated from high school

Alongside a snap of herself and Abby, 18, at the event, she wrote on Instagram: "Tears of joy for my incredible niece @abbyjameswitherspoon ! Congratulations on all the hard work, long hours of studying , the endless hours of test taking and essay writing ... and biggest congrats on being the joyful, kind-hearted, energetic, funny girl we are all so proud of! [heart emoji, graduation cap emoji]Such a proud aunt."

The 'Legally Blonde' star- who has Ava, 24, and 20-year-old Deacon with her first husband Ryan Phillipe as well as son Tennessee, 11, with her second husband Jim Toth - graduated from the private college-preparatory school for girls herself shortly before kickstarting her Hollywood career with roles in films such as 'Freeway', 'Fear' and 'Cruel Intentions'.

Despite being proud of her niece's achievements, the 'Morning Show' star recently tried to encourage parents to discuss their children's failures at school as well because she thinks that kids need to experience the "discomfort" of not reaching a goal.

Speaking on the 'Good Inside with Dr. Becky' podcast, she said: "I see this a lot with parents - I don't know when we stopped letting our kids fail. Like I learned so much from the paper I didn't turn in or the demerits I got, so I got detention.

"And my parents didn't say, 'Uh, she didn't deserve that.' And take me out of school.

"They actually let me sit in it, and feel uncomfortable. So I think, learning from failure is actually a valuable tool that you can't take away from kids, right? "You rob them if you don't let them sit in the discomfort of the experience."