If you want to write well then you need to know/understand your characters, there is no better way to ensure this than to write from within yourself, using your own experiences. This article perfectly explains why characters written in this manner will be more believable and sit in more depth than ones that aren’t. I’m having so much fun free writing about characters and experimenting with the trials and tribulations I think they have been through. This really highlights that for me
The gap between what the characters wants and their needs are where the most interesting aspects of your characters will reveal themselves. And both want and need are created in really knowing your characters as if they were you.
How you gonna do that if your characters aren’t in your likeness or the likeness of those you have met/know even just a little bit? That and limitless imagination is in my mind the best combination for a genuine character :D