You're thinking, therefore you are a person.

But I think feeling things make you even more of a person. Empathy, sympathy, they're all important. Caring for others makes you a better person, too. Not that you should never be selfish, because you should - you, as a person, comes first.

I don't think you can only be part of a person. I think, the second you have your own thoughts, you are a person, and that's that.