i am almost baffled by the situation

[genkaus]

rational evaluation , what is that ?

To determine if the action was directed to a specific purpose, if the purpose is morally justifiable and if the action is justifiable according to the same moral code.

your child changes your life , takes your time and money .you feed him, you give him proper schooling, proper food ,clothes and your own comfort to make him comfortable. why ?. on rational ground he is messing your life then why you feel happy to see him happy. give me rationale.
edited by leo-rcc: fixed quotes

Are you suggesting that having and raising children is a meaningless endeavor?

For any unwanted pregnancies, it probably is. But for couples who actually want children, it is can represent a crucial step in self-actualization.

For those who actually want children (as opposed to those who simply have them due to accidental pregnancy or a sense of social responsibility) - a child represents a great amount of value. The happiness and satisfaction achieved from raising the child to be a productive human being is far greater than anything else the money invested in that child could buy. For those people, putting in all that time and effort is not messing up their lives, it is an investment in their own happiness and the results are often well-worth it.

And your idea that parents are happy (or should be), if the children are happy - irrespective of the reason for that happiness - is incorrect. A drug addict may be considered to be quite happy. I doubt if his parents are happy for his happiness as well.