There are stories in all of us, and the old adage "write what you know" is always a good place to begin and keep coming back to. It only makes sense to steal and/or elaborate from your own experiences.
Before I had children of my own, I avoided writing scripts with kids as main characters. I didn't understand the complexities of the parent/child relationship, at least not from the parent's point of view. Now, however, children are an intricate part of my everyday life, so writing about them is much easier. I simply write what I know.
Take Eugene O'Neill, one of America's greatest playwrights (Beyond the Horizon, The Hairy Ape, The Iceman Commeth), as an example. The father of American drama, O'Neill won the Pulitzer Prize four times and is the only dramatist to date to win the Nobel Prize for Literature. And even O'Neill drew heavily from his own experiences, and often. His award winning play Long Day's Journey into Night - widely considered his masterpiece – is a deeply autobiographical account of O'Neill himself, his older brother, and their parents at their home during one fateful, heart-rending day at their Connecticut summer cottage.
Edmund, like O'Neill, is a writer of fragile health who was treated for tuberculosis for six months in a sanatorium. True. Mary, molded after O'Neill's mother, is a morphine addict. Also true. Jamie, like O'Neill's brother, is an alcoholic whoremonger. Again true. And James, just like O'Neill's real-life father of the same name, gave up a promising career as a Shakespearean actor for a part in long running commercially successful yet artistically void play. True. True. True.
This isn't to say that you must write stories that reveal your own life so literally, nor am I suggesting you should never explore material that you don't know intimately, but whatever you decide, use logic as your guide. If you never watch rom-coms, why are you going to write one? If you're not into sci-fi, why are you going to set your world on another planet?
But remember that knowledge is also your experience. You may never have been in the military or stepped foot in Iraq, but if you do the research - interview people who have and read everything you can get your hands on - your knowledge is the learning experience that is necessary to write the script.