"It was just that," said Kutcher. "I just didn't think it was fair what was happening. So I knew there had to be a blood type match, and he's my twin. So the assumption would be that we would be a match -- but that doesn't all compute. We were fraternal twins. I started studying genetics right after that, and it doesn't work that way.
"It wasn't a good plan anyway ... 'cause wouldn't that have been the worst, to jump off and then they would be like, 'You're AB! You're an A-plus and he's AB, it's not a match. What're you thinking!'"
Kutcher focused on his studies, but then life took an unexpected turn. He was discovered at a "Fresh Faces of Iowa" competition.
"My parents couldn't give me a whole lot of financial support," said Kutcher, "but they gave me good genes. My dad is a handsome son-of-a-gun, and my mom is beautiful. And I've definitely been the lucky recipient. So, thank you, Mom and Dad."
Kutcher quit school and became a top male model.
"It's hard to appreciate success in modeling, because it's not something you feel like you've earned, so there is a little bit of bread of shame that comes with that," said Kutcher. "It's like somebody giving you a puzzle that's already put together. There are some things you have to do to maintain, but it's like getting a 1,000-piece puzzle and having two pieces out. ... It was hard for me to feel ownership as a model."
So Kutcher quickly leveraged his modeling career into acting, landing a starring role on the Fox hit "That '70s Show." Stardom came with perks: money, fame and a string of beautiful starlets, including January Jones and Brittany Murphy.
Kutcher met Murphy on the set of the 2003 romantic comedy "Just Married," and the two began to date.
Last year, tragically, Murphy died at the age of 32.
The coroner ruled the cause of death pneumonia, but there were persistent rumors of Murphy's prescription drug abuse.
"I don't think you can," said Kutcher. "I don't know if you try to make sense of it or not. I just celebrate who she was. She was like the person who walked in the room and she was always like the first person to dance.
"You know when you go to a party and everybody is standing around, and the music is going, and you know, sooner or later everyone is going to dance. She was always the first person to dance. And I just try to connect to that and celebrate who she was and how she was, and not make sense of it, 'cause there is no sense of making sense of it."
Were they still in touch?
"Not really," said Kutcher. "I mean she came in, we were casting a TV show that we were producing, and I wanted her to play this role in it. And she came in, and I got to see her probably about two months before she passed away."
Kutcher played the role of dim-witted Kelso on "That '70s Show" for eight years.
Then he delved into film. He played a dimwit in the movie "Guess Who" and another dimwit in the film "What Happened in Vegas."
"That's what I knew how to do," he explained. "That guy's a little daft, lazy, getting by on his looks and not a whole lot else, and sweet, and likeable, blue-collar, that guy... funny sometimes. That's what I knew how to play."
Is that who he was?
"No, that's who I got really good at playing."