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For simple herd helpers, only 1 gene needs to be specified to achieve the stated color or quality. For more complex herd helpers, multiple genes need to be specified. This is achieved by triggering the primary herd helpers needed to control all the genes required for the specified color.

Both of you went way over my head... sorry.

Thank you... I actually understood that!
What are the odds of getting both A and B?
Thank you, all 3 of you.
Hmmm... would a horse that has multiple triggers be worth more in a sale than a horse with just 2?

I looked back and can see I phrased my question wrong. What are the odds the foal will inherit both A and B?

I'm sure there is a detailed explanation (with diagrams) about how genetic inheritance works somewhere. In the meantime I'll give it a go.

All the genes come in pairs. If you have ever bought any of the limited edition genes from Ammit to put on a horse you will see that you have to choose DNA Strand 1 or Strand 2 to put the gene on. Every horse has a pair of genes for each characteristic. When they are bred a copy of ONE of each pair is passed to the foal, so the foal gets one copy from its sire and one from its dam and ends up with a pair of genes.

Let's take the example of a Silver Black. We'll assume that you have a stallion that is homozygous for both genes. That is EE for the black and ZZ for the silver. You can see that whether the copy of a gene comes from strand one or strand two it can only pass on an E and a Z to the foal. We'll assume you choose a mare that has neither of the genes and is ee (red based) and zz (no silver). She can also only pass on an e and a z. The resulting foal will be Ee (black) and Zz (silver).

If you are still with me, we'll have a look at what happens when that foal (who is still a Silver Black in appearance) goes on to breed.

So the foal (we'll decide it's a stallion) gets crossed with a mare who just happens to have the same gene pairing, that's Ee Zz. There are four possible outcomes for EACH characteristic, that's sixteen in all! But don't worry, you won't get sixteen different colours. :)

If the foals get a copy of E from each parent they will be EE and black (one in four chance). If they get an E from one parent and an e from the other parent they will be Ee and black (two in four chance). If they get a copy of e from each parent they will be ee and chestnut (one in four chance).

The same possibilities are likely for ZZ (one in four silver) Zz (two in four silver) and zz (one in four not silver). As silver only affects black horses then the resultant chances are:-

Silver Black - 8 out of 16
Black - 4 out of 16
Chestnut - 4 out of 16

You can see how the more genes you are looking at the more complicated it gets. I hope I haven't confused you too much.

yes... I saw the Punnett Square a couple of times, thank you for reminding me... and White Valley, you just cleared up my confusion about it. Thank you both!