Mysteries at every step

I don't get it. How do people dare to have children when there are zero guarantees about the outcome, without having no idea about what kind of a person their child will grow up to become? How do people deal with the fear that their own fresh and blood may turn into a major disappointment? My guess is people don't think at all which is truly perplexing when it comes to an issue such as having a child that should be approached with utmost consideration.