Is Ditto a Failed Mew Clone? This theory got some attention on the internet a few years back, but I haven't found a definitive source on it.

Both Ditto and Mew are genderless pokemon, with similar color schemes for both their normal and shiny sprites (images from Serebii.net):



The ditto normal sprites are somewhat more purple than the Mew sprites, but earlier generation Ditto sprites were a bit pinker, and the shiny sprites are almost exactly the same color.

In addition, both Ditto and Mew weigh 8.8 lbs (4 kg). They both learn Transform naturally at level 0. There are a bunch of places where Ditto can be caught in the original generation I games, but in Yellow the only two places are the Pokemon mansion (where Mewtwo was cloned from Mew) and Cerulean Cave (where Mewtwo lives). Mewtwo is also called the only "successful" clone of Mew, so there's reason to believe that there were failed attempts, which could be Ditto.

Of course, everything above is just fan speculation, but it's gotten a fair bit of attention and I'd imagine someone from the Pokemon Company has commented on it. What's the official word on this theory?
According to an GameInformer interview with the art director and the producer (Junichi Masuda) from Gamefreak:

There is a rumor that in the original Pokémon games, versions Red and Blue, that the Pokémon Ditto was a failed attempt at cloning a Mew. I was wondering if you could speak to this, to whether or not it’s true.
Masuda: That’s the first time I have ever hear that rumor actually.
Is that your only answer?
Masuda: In terms of how Pokémon are designed, they are each their own unique living being. The unique thing about Ditto is that it’s a Pokémon that can change forms, but each Pokémon we create with its own unique element, so we just make sure that they are all individual life forms of their own.

Though it seems that his response denies this theory (or rather skirts around it), but since he was probably not directly involved in the development of the game, it's still possible that Ditto was originally meant to be a failed Mew, but scraped somewhere during in the development cycle.