Nobody has any idea how your kids will turn out - we have even less control over this than over how our marriages will turn out. But best of luck to you.
There is no dichotomy between rational decision making and having kids, or any other thing that you might want to do for yourself or others.
Thinking decisions through and being honest with yourself is a GOOD thing, particularly in the case where it will affect the rest of your life and the welfare of one or more children. Rationality is a value.
Nobody has claimed to be an amazing savant. People do have different priorities and not everyone is the same as you. If I like salt and you do not like salt, then each of us can be rational while doing a completely different thing.
If you mean to show that reason has limits and that it has terrible consequences then unfortunately you must use reason to show that, and I cannot see that you have done that.
Many people are sterile and cannot have kids. They are still alive by any definition. Many people decide not to have kids but are good Aunts or Uncles or adopted parents. Many decide not to have kids but take care of them, teach them, mentor them. There are even, god help us, productive people who don't have anything specific to do with children. That doesn't mean their existence is meaningless.
On the other hand, a man who spreads his genes by rape may be having lots of kids, but he is not doing a good thing, and is probably not leading a deeply fulfilling life.
The case of adoption and the case of rape say pretty clearly to me that love is more morally fundamental than differential fecundity.
The moral purpose of your life is not given by population genetics in any case. It is an error to conflate purpose in the adaptationist sense with purpose in the sense of your life's fulfillment or your moral values.
Different people are suited to different ways of living, and find different forms of fulfillment; it is part of what makes life varied and interesting.
It is not necessary or helpful to be uncivil about this.
altrego99 is expressing a considered personal view with which you disagree, not insulting you or the mass of humanity. You are entitled to your personal view as well. But you could recognize consideration of the issue as a good thing and the disagreement as normal and healthy. Instead, you are calling people terrible names and picking on grammar, without provocation. Please don't continue in that vein.
I think for most people, you are right that having a kid is a fulfilling thing. I am personally glad that someone is having kids (particularly if they are doing a good and thoughtful job of caring for them). But the implication that no one with kids could ever disagree with you is not correct - though it is unlikely that they will bother to do so in public. I have talked to several people who do regret having kids (particularly in a certain time or situation) but they are not so likely to say it - both because of the kind of aggressive reply you have given but maybe also because they are likely to be wrongly taken as saying that they do not love their children, or that they wish the child did not exist. A person can believe that having kids is not necessarily altruistic, or that there is no moral or practical imperative to have kids, without being an awful arrogant psychopath.
Before you have a child, there is no child to wish the nonexistence of. And since it is an irreversible long-term decision, you should definitely think about the pros and cons in a rational way. Many people do come to parenthood by a reasonable, conscious choice and that is a blessing. Other people decide not to. If that is in their best interests then good for them. Perhaps there will be a future time where it does make sense to have kids. Leave them be. It's a personal decision, not a moral necessity.
Not everyone has to get married, either; not getting married doesn't make you a psychopath or a pathetic unfulfilled person, even if it's a nice thing and a great life work for many people.
I don't know what it's like in San Francisco.