I guess the main thing to remember if you are thinking about genetics is that dominant genes only require one copy and recessive genes require two copies in order to be visibly present. Dominant does not mean that it will override ever other gene, just that it only requires one copy to be visibly present. Each chick gets one gene from it's mother and one from it's father. Then, you look at how those genes might be present to see what you might end up with. If we take an easy example, the pea comb which is dominant gene. The parent that shows the pea comb could either have one copy or two copies, let's call them Pp or PP. If you breed to another bird that has a straight comb, it's gene combination would be pp (because it doesn't have a pea comb it does not have a copy of P).
Now lets look at what the possible combinations could be (use a punnet square, makes it easier to see). If the one parent has one copy, the resulting combinations would be Pp, pp, Pp, pp. So, 50% of the chicks would have one pea comb gene. If the one parent has two copies, the resulting combinations are Pp, Pp, Pp, Pp. All of the chicks would have one pea comb gene and show the pea comb.
So, that is the basics. I won't go into what happens when you breed two birds that each have at least one dominant gene for the same trait (i.e. the pea comb and the rose comb are both dominant). That lesson is for another day.
What interests me the most about genetics is that you can tell what genes the parents have based on what the resulting chicks look like. For instance, if you breed a pea comb to a strait comb and 1/2 of the chicks have the pea comb, then you know that the pea comb parent only has one gene. If all of the chicks have pea combs, then you know that the parent has two genes.
Hope that makes things a little clearer. A few common examples of dominant genes: pea comb, rose comb, vulture hocks, 5 toes, feathered legs, crests, frizzle, wildtype (gold), white skin, tufted.....and on and on. Sometimes the presence of two dominant genes gives a different result than expected, but those are unusual. Blue is one of those color genes that when two are present the result is splash (not dominant white which is a different color altogether). So, how do you know if you have a blue splash vs. a dominant white? Breed to black. If the resulting chicks have white on them then the parent was dominant white. If the chicks are blue, you have a blue splash.
Lesson over........
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