Since the latest patch of 2-5, the OT will pass on from the female or non-ditto parent. This patch as far as I have noticed brings more harm than good, and therefore I'd suggest undoing it. The patch harms both the breeders and sellers.
With this patch female breeders won't be sold as much as before, and a player will not be able to breed each pokemon they like when they like if they have the funds. For example, I bought a feebas before the patch, which I now can't breed the OT on, and it isn't catchable as well.
Next to that the breeders probably spend a lot of time, money, and pokemon when breeding their pokemon. And if that did not start of with a pokemon they caught theirselves, they won't even obtain the OT status on their pokemon. This also seems unfair, as someone who spend such an amount of effort breeding a pokemon would deserve the OT status more than someone who threw a pokeball at one.
With this message I'd like to see if this problem is as big as it seems, and what the rest of the community thinks about it. Hopefully we can get to a solution which best fits the game.