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.
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.