I remember listening to Alice Walker, author of iconic books such as The Color Purple, speak at UC Davis. I was about 20-years old. She talked about life and experience. One thing she said was that she didn't think writers had anything to really say until their 40's. I was 20 -- and this was discouraging. At the time I remember defiantly thinking I had plenty to say. Well years later, I think I'm inclined to agree. I really didn't have any life experience to draw on. I could imagine the feelings and the experiences all right, but did I understand the "heart" of the experience? No. I had no resources to draw perspective.
Fast forward to my 40's, and I've had plenty to say and much experience to understand. In my new book Body in the Trunk, the story revolves around a paranormal romance and duplicity. Having a much broader experience with different kinds of love helped create the layers of emotion in the story. It enabled me to give the character's reactions authenticity. It didn't matter if I had actual experience with the situations as it mattered that I had a viewpoint to offer. Knowledge of appropriate behavior and probable responses.
I'm not suggesting that young writers can't be exceptionally talented and offer the same kind of knowledge. I certainly had plenty to offer when I was a young writer. What I'm saying is that experience and wisdom help give realism to your stories. A pool of knowledge helps guide the writing. It's also helpful if you've gone through the actual situation to draw from real-life experience. Again, it's about authenticity. Your work is more likely to have an authentic quality when you know exactly what you're talking about.