Fucking the natural order

A couple of years ago, scientists in the US achieved an enormous breakthrough: they took stem cells from a mouse, artificially differentiated them into sperm, and fertilised an egg with the result. Now, they've begun duplicating the process in humans, successfully differentiating human bone marrow stem cells into spermatagonial cells, the precursors of sperm. It's only the first step, and there's still a long way to go, but if it pans out it will see us able to differentiate both sperm and eggs, vastly increasing the range of infertility problems which can be treated, as well as allowing gay couples to have kids using only their own genetic material (gay males would obviously still need to find a birth mother). And given the centrality of children to many people's lives, and the degree of unhappiness infertility can cause, IMHO that can only be a Good Thing.