Well, CF is caused by a mutation in our gene structure. Our genes determine how our body is built. You might think of it as a blueprint or a set of instructions. When you were in your mother's womb, you started out as a single cell. That cell contained two genes, one from your mother and one from your father. As the cell divided into more and more cells, they followed the instructions from your genes, and that is how they made your body.
With CF, however, there is a mutation in both your genes given to you by your mother and father. There is something wrong with the instructions that your cells followed. Because of that, the cells made a mistake when they were building your body, and that is why we have cystic fibrosis.
As for having babies, there are many women with CF on this site who have children. Pregnancy does put a strain on your body, and so there are some helath risks. Just because you have CF doesn't mean you can't have a baby, it just means you have to be a little more careful.
Also, because you have CF, you are 100% likely to pass at least one CF gene down to your child. The reason your parents may not have CF is because they have one regular gene and one mutated gene. In other words, your parents cells had at one set of correct instructions and one set of incorrect instructions so their cells followed the correct set of instructions, and their bodies were built correctly. When a person has one normal gene and one CF gene, they are called a carrier.
Now, if you have a child with someone who has two normal genes, all of your children will be carriers; they will have one CF gene from you, and one normal gene from your partner. If you have a child with a carrier, then your children will be 50% likely to have CF, because there is a 50% chance your partner will pass down the CF gene and 50% chance he will pass down a normal gene. If your partner has CF, then there is a 100% chance your children will hve CF.
I hope I helped to answer some questions. Please don't hesitate to ask if you have any more.
