The first Jurassic Park handled mature themes very well, while still keeping the movie accessible to the family as a whole. Spielberg made controversial and complex concepts such as cloning work at a mature enough level while still keeping the film fun and (to a certain extent) child-friendly (and lets face it, a lot of us were very young when we were first introduced to Jurassic Park, and I'm sure it captivated all of us, otherwise we wouldn't be discussing it right now).