For parents: When you first decided to have children, was their happiness foremost in your mind?

I am posting this question, because it seems to me that many people who have children do so for selfish reasons. They often decide to have children, simply because they "want" them, but they don't take into consideration whether it's a good idea. For example, there are people who have hereditary mental and physical illnesses, yet they decide to have children, despite the fact that their children could very easily inherit their conditions and suffer the same misery they have. Not only that, but there are people who can barely afford to support themselves financially, let alone another human being, yet they decide to have children, because they don't think of the deprivation their children will experience. Before people have children, shouldn't they take into account how much suffering their children may experience if they're born into the cirstances in which their parents are living?