It's all hormonal response, sure, but ultimately anything that gives you satisfaction is ultimately just ways of manipulating your neurotransmitter levels. Having kids just happens to be one for which your body has a built-in response that gets you seriously drugged up.
How old are your kids? Even with the special bond parents can have with their children that's not a guarantee things will be good. I know awesome parents who have raised horrible people. I know awesome kids who turned into horrible people after they left the nest. Most people seem to eject their aging parents into nursing homes when they are too old, because people would rather live their lives than take care of their parents. Good friendships last forever and don't require you to change diapers in the early years while convincing yourself its all worth it for the few golden moments if you don't happen to be forced to miss them because of work or just chaos.
Convincing me to want to have kids would first require me being convinced that I should want to ever get married. :)
Be wary of friendships which are one sided. If a person doesn't value their own person and they constantly need you to help them that's not friendship it's dependency. I've never ejected people out of my life the first time they needed help, but I have given up on people when I realized I was wasting my time. Many people who need help can only change with their own effort.
Every relationship is one of opportunity. Think about that!
This is true. However, if the causes for this attitude (biological or cultural) are in some way heritable, we can expect that over several centuries the attitude should disappear, or at least be significantly curtailed. (It is not clear exactly to what extent this is actually the case.)
No opinion is offered on the moral import of these matters. However, any future anthropologists will have something fun to study, surely.
Most people who seem stupid are only stupid because they lack what equally capable, but perceived as gifted or intelligent, people have. Most people have much the same genetic wetware capabilities - brain damaged people an exception - the biggest biological differences between most people are in hormones, and changes in hormones are largely a product of environment and can be changed just as knowledge can be changed. A human's potential is able to be expressed with an abundance of knowledge and the lack of enforced ideology. Allow people reference, perspective, and freedom and they will seem like smarter people than whose without. The sooner people have the best situation the better but it is never too old for someone to get smart.
Somehow, this line reminded me of Huxley's "Brave New World".