Michael Kutcher, who is Ashton's fraternal twin, was born with cerebral palsy and has suffered from heart problems throughout his short life - needing an emergency heart transplant at the age of 13.
And while Ashton shot to fame in the acting business, bagging himself a string of glamorous ladies and serious bucks for his movie roles, Michael had to settle for living in his brother's shadow.
“I was the kid with the big Coke-bottle glasses, the hearing aid,” Michael told Details magazine.
“There was a lot of teasing, a lot of the normal mean stuff." As a result, high school hunk Ashton made sure his brother - and anyone else for that matter - didn't get bullied.
“That was a big part of my life,” says Ashton, “kind of looking out for my twin.”
Maybe a little too much - when Michael required a heart transplant in 1991 after developing the heart disease cardiomyopathy, an emotional Ashton had considered throwing himself off the hospital balcony - so that his death could save Michael's life with the donation of his healthy heart.
"I'm standing on the balcony, thinking about jumping off, and my dad comes out and says, 'What are you thinking about?'" Ashton recalls.
"I tell him. He comes over and says, 'You can't do that' - and right then the doctors come rushing out, (saying), 'We have to prepare the OR. A woman died in Florida in a car accident, and there's a heart on the way.' " Now that's good timing!
There are celebs out there that have twins you've never heard about - besides the obvious Olsen/Origiasso/Madden twins, the likes of Scarlett Johannson, Gisele Bundchen and the Napoleon Dynamite guy have all got doubles! Check out our gallery below to meet them...