To look at the problem from a different angle ,the question we need to ask ourselves is as follows:
How come that the human beings NEVER FAIL to produce offsprings in which an intelligence ( doesn't matter how we define it in this context ) EMERGES with probability close to 1 ?Bear with me, this is really profound - we can restate it in a different way:
There exists a set of conditions , ( both external and internal relative to the system in question), which when satisfied will render an intelligence emerging in that system ( again, doesn't really matter how we define it ) with probability higher than 0 !
If you look at it this way, it will be difficult to prove , that one of the conditions should state that the system should be an offspring of a human species, or even be biological in a sense which we require it to be. It's also, I think is a much more interesting venue of research to pursue, instead of building an A.I. through modeling of cognitive processes.