By Silverheart
Original Post
More information are discussed in the original post. If you have any other questions or information that is not included there, please feel free to leave a note in our forums.
Because I'm a geek, because I've been seeing way too many mislabeled ponies, and because I was the weird one in high school biology that not only understood genetics, but was actually interested in it. :D
Dominant gene | Recessive gene
Let's take basic human genetics here for a moment. Parents of a child are both brown eyed. Their child has blue eyes. What does this mean? What happened?
Although both parents show brown eyes, each one carries a gene for a blue eye from several generations back. Since brown is dominant over the recessive blue gene, neither may even know this. But because the child received BOTH of those recessive genes, he/she ended up with blue eyes. (I actually know someone where this is the case if anyone doesn't believe me.)
Oh…and I know there are other possible answers, but life is not the Maury show. Really. ;)
This works the same in PI genetics.
There are three locations for visible Sgenes in PI. Hair, Body, and Feet. These three locations have two possible Sgenes each. One of the genes will always be Dominant and one will always be Recessive. That is how genetics work. (And PI's Sgenes are genetics in their most simple form, really.)
Hair Genes
Stripe is the dominant gene. Rainbow is recessive to Stripe. Tips are recessive to BOTH. A pony will show a stripe if he or she has two Stripe genes, a Stripe and a Rainbow gene, OR a Stripe and a Tips gene. A pony will show Rainbow if he or she has two Rainbow genes, or a Rainbow and a Tips gene.
Therefore, a pony will ONLY show a tips if he or she has TWO Tips genes.
What does this mean?
You CANNOT have a pony that is a "stripe carrier and rainbow carrier", or any combination of the three genes. If you did, the pony would have a visible sgene.
You COULD get a baby with tips out of two stripe parents if they both carry a Tips gene and both manage to pass that gene to the baby.
Body Patterns
Like with the hair genes, Paint is the dominant gene. A pony may show a painted body if he or she has two Paint genes or a Paint and a Zig Zag gene.
Thus, a pony will ONLY show a zig zag pattern if he or she has TWO Zig Zag genes.
What does this mean?
You CANNOT have a pony that is a "paint carrier and zig zag carrier". If you did, the pony would have a painted body.
You COULD get a baby with a zig zag pattern out of two painted parents if they both carry a Zig Zag gene and both manage to pass that gene to the baby.
Feet
Now, this gets a little complicated with the introduction of fades.
Socks are the dominant gene. Stockings are recessive to Sock. Fade is recessive to BOTH. A pony will show socks if he or she has two Sock genes, a Sock and a Stocking gene, OR a Sock and a Fade gene. A pony will show Stockings if he or she has two Stocking genes, or a Stocking and a Fade gene.
Therefore, a pony will ONLY show a fade if he or she has TWO Fade genes.
What does this mean?
You CANNOT have a pony that is a "sock carrier and stocking carrier", or any combination of the three genes. If you did, the pony would have a visible sgene.
You COULD get a baby with faded markings out of two socked parents if they both carry a Fade gene and both manage to pass that gene to the baby.
In short:
Type | Dominant | Recessive
Hair | Stripe | Rainbow | Tips
Body | Paint | Zig Zag
Feet | Socks | Stockings | Fade
If your pony carries two genes from one line in the above chart, they will be a visible Sgene in that location. A pony can carry ONE gene from a line and only be a carrier. A pony can carry ONE gene from EACH line and only be a carrier. But the minute that a pony "carries" TWO genes from ONE line, the pony will show a visible Sgene.
