Also, Red Slates do not have any red genes. The birds have that color because they only have one copy of Bronze. It is like half Bronze. For example:
You have a bucket that holds two cups of paint. Each cup represents a gene.
The bucket has to be full at all times.
A Bronze turkey has two cups of brown paint in its bucket. So, two brown (Bronze) genes.
In the Red slate, there is only one cup of brown paint. (One brown gene).
Since the bucket has to always have two cups of paint in it at all times, and there is only one cup of brown paint, there is a cup of white paint that gets put in. (This doesn't represent a white gene, just a medium that dilutes the brown paint. You could also say water.)
When the brown and white paint mix, you get this copper-y red color.
This is what makes the red show up in the Red Slate. It has slate genes, and only one bronze gene. So the filler gene, that gets mixed in with the Bronze, makes it look reddish and slate.
Bourbon reds use actual red paint. And they have two cups of it. This looks like "rr". But red paint is real watery and weak, so for the turkey to look red at all, it has to have two cups. If it has only one cup of red, like if you cross it with a slate bird, the bird would come out looking like a slate. It would be "Dr". The slate gene (D) is capitalized because it is a dominant, thick kind of paint.