Ashton Kutcher wanted to give his own heart to his twin brother, when he needed a transplant at the age of 13.

The 40-year-old actor's twin brother Michael is alive today because of a heart transplant he had when he was diagnosed with cardiomyopathy - in which his heart grew to be four times the size it should be - when he was a child.

And Michael - who is living with cerebral palsy, a permanent movement disorder - has revealed he has a ''deep appreciation'' for Ashton, as he was willing to give up his own life to save Michael, before another suitable donor was found.

Recalling the 'That 70s Show' alum's generosity, Michael said: ''It's just ... I can't find the words. It's a connection that you can't explain. In all seriousness, we're just very connected ... It's an honour or deep appreciation and a deep love for someone who would sacrifice that for you. I really can't put words to it.''

Ashton has previously said that Michael taught him people are not all created equally, but Michael insists he doesn't want people to ''feel sorry'' for him, because he doesn't think he got ''the wrong end of the stick'' by being born differently.

He said: ''I think his quote of [how] not everyone's not created equally, I think that goes back to him feeling sorry for me at a point. He's right. We aren't created equally, whether it be a disability or a health issue or whether it be anything, ethnicity, sex. We're just not created equally. If we were, what's cool about that?

''I don't really like to use the word disability, I like to use the word giftability because we're all created different. We all have disabilities. I think his quote is right on. We're not born equal, but that's okay. It's okay. You may think I got the wrong end of the stick, but having the transplant and the disability and everything, but in my eyes, I got the right end.''

Michael also revealed he encouraged Ashton not to pity him, because he believes he was ''put in [his] situation'' in order to be an advocate for disability and organ donation.

Speaking to Us Weekly magazine, Michael - who now works with the #BeTheGift campaign, which encourages people to register as organ donors - said: ''I am who I am, right? I was put in these situations. Who I am is for a reason. I strongly feel that a major part of that reason is to be an advocate and be outspoken and use the platform that I am to advocate for disability, to advocate for organ donation, and I feel I've found my purpose in that.''