I can appreciate the idea that one's work can (potentially) function as a superior alternative to children, with respect to legacy. In general, I'm all for elevating the rational part of Human mind. On the other hand, I think it's dangerous to describe the reproductive priorities of the "primitive" mind as a "silly desire". To put it more concretely, imagine a husband who has just learned that the children he's dedicated years of financial, emotional, and educational support are not his own. Imagine the gamut of emotions that cross his mind: anger/hatred toward his wife's deception; the humiliation that comes from being deceived; the conflict that comes from both loving the children, yet despising them for what they represent. How do you think that man would respond if you told him that his feelings were the consequence of a "silly desire". It's all well and good to have a world with gay uncles that support their nephews and nieces; but somebody's gotta make those nephews and nieces.