IF GOD IS PERFECT WHY WERE HIS CREATIONS FLAWED?

How can a perfect god make creations that are flawed? If the first people were genuinely perfect, and had a nature that was perfectly good, why would they ever desire to do anything evil. the desire for evil had taken place in a creation who was at the time supposedly perfect, perfectly good natured and everything. A god would have free will but still never desire or choose to commit sin,and surely he has an appreciation and understanding of good, why couldnt an all powerful god create his creations the same way, preventing evil?