As in, could we manipulate a spermatozoon or an ova and force a pair of either of those to bond? They both contain half the number of chromosomes necessary for a human being to form. Of course, women contain two X chromosomes, while men contain one X and one Y, so I'm assuming that, if this were possible, women could only give birth to other women.
By "manipulation", I mean manipulating the gametes; not the people themselves. I guess what I'm asking is if it's possible to turn a spermatozoon into a functional ova and vice-versa, without harming the child that would come out from such a cell and without changing the characteristics that a spermatozoon/ova would "give" a child, if it had always been a spermatozoon/ova and had fused with their owner's respective sexual partners' gametes.
If this is possible, how long would it take to figure out how to do it and how long would it take to actually do it?