Each time I mention mutations my wife says she wishes I would mutate into George Clooney… Sigh … 
Looking forward to vocab now… Thanks both!
Steve (Catflap): There’s a moment coming soon where those peskie mutations are going to start feeling really natural.
The trick is to remember that “natural” and “accurate” are two different things. Ioan and Emrys mutate totally naturally, sometimes perfectly and often wrongly. More to the point, I mutate perfectly naturally (without thinking), and sometimes get corrected by my 7 year old son.
Natural is a state of mind. If you are trying to mutate correctly, you won’t be mutating naturally. If you are mutating naturally, then you won’t be mutating 100% correctly.
One or the other - you choose!