Here we have a simple illustration of "heredity" and "variation."
Now, could we blame the "child" bottle for having red and blue beads in it; or could we blame the "child" bottle for having no yellow and no green beads in it?
But that is an example of a simple mixture of two ancestral strains. We have to do with mixtures of millions of strains.
Let us carry our illustration forward another generation.
Take our blue and red "child" and marry him to the child of a black bottle and a yellow bottle.
This gives us a marriage between Red-Blue and Black-Yellow.
The "child" bottle mixed from these two bottles of double colours will contain four colours.
He will "inherit" from grandfather Red and grandmother Blue, from grandfather Black and grandmother Yellow, and from father Red-Blue and mother Black-Yellow.
He will be like the six fore-parents, but different from each of them.
Can we blame this "child" bottle for being made up of red, blue, black, and yellow? Can we blame it for having no purple nor white beads in its composition? No. These colours were mixed for the child, and not by it.