At the beginning of this year, we paired up some groups of siamese rats.
Every now and again, we would get a ‘runt’ or two in a litter that looked nearly hairless.
We nicknamed them ‘Dobby’
These we kept back and puzzled over for a while.
The only thing we could think was recessive rex at play causing a visual double rex.
The only way to be 100% sure was to grow and breed two from separate litters together and hope for full litters of the same.
A few weeks ago we proved this 3 times over with 3 different female Dobby’s producing full recessive double rex litters.

So what does this have to do with satin?

Whilst that was going on, a few of the siamese mothers of Dobby’s were being introduced to some rex Martens males.
The babies they produced were straight coat and rex. 
As they grew, a few of the rex were noticeably more wavy and shed their baby fur almost to a point of being nearly bald. When it grew back, a satin sheen came back with it.
It was only when reading up a little more and talking to another breeder that we discovered satins need a co-dominant (visual) rex and a recessive rex they are compatable with each other to produce satin.

Turns out our little blessing of recessive rex genes in our siamese have also blessed us with satins too!