Is this based off of any stories or books ?

"I am Sam" has an original screenplay (so no previous book or anything), and it is not based on any true story. I was trying to think of other movies with a similar story; a parent or parents with developmental disabilities who have a child, and there is concern the child can be properly cared for.

The only one that is coming to mind right now is based on a true story and was made into a CBS tv movie made a few years after "I am Sam." It's called, "Profoundly Normal," starring Kirstie Alley and Delroy Lindo. For a tv movie, it's actually quite good. It tells the true story of Donna and Ricardo Thornton, both raised in an institution and have "sort of" on the cusp of mild to moderate developmental delays.

They left the institution and eventually married and had a healthy baby boy in 1986. For both their marriage and having a child, the state was concerned they couldn't manage either. I'll stop there with the story-telling, but that CBS movie is pretty good, and the true story is really interesting.

I can't think of any closer to "I am Sam." A 1970s tv movie with David Cassidy's brother, Shaun and Linda Purl starring, titled, "Like Normal People" features a young adult couple who want to marry, but because of their developmental disabilities, they meet with resistance. It's actually on Youtube in nine or ten parts, and I'm pretty sure this movie was inspired by a true story.