According to an article by Dr. Lucas, published earlier this year,
"The traditional way to look at multigenic traits is to assume that each gene of several contributes some increment of effect to the phenotype. If we called that 'A' and there were four sets of alleles we could array them from AAAAAAAA through AAAAAAA+, AAAAAA++, AAAAA+++ and so on down to ++++++++. This is one way to try to account for variation that seems continuous rather than either-or. This has been a useful and generally satisfactory way to try to explain such variation although I always thought it looked best on paper. It doesn't logically seem easy to explain how such a system could have developed through random mutation. There are, of course, ways to try to account for it but that's another topic. This interpretation is more the way variation of red and the iridocyte colors operates. For general purposes the Er and Si designations can be used as though they were single gene designations but one needs to remember that the results are not going to work in strictly that way."
Later in the same article he states:
"In Crown Tails, or what I prefer to call Fringe Fins since other fins beside the caudal (tail) also have ray extensions, the rays extend beyond the edge of the membrane portion of the fin. I think that what happens is that the membranous portion of the fin does not grow as far out as the rays themselves, thus it appears that the rays protrude. Another problem I have with the term 'Crown' is that it doesn't work for more than a few of the affected individuals. The membrane seems to extend slightly further between the branches of the rays than it does between the main rays themselves. If one rotates the tail so the rays stick up and the extension is right, the contour does resemble a King's (or Queen's, Princess's, etc.) crown but the trouble is that only certain ones meet that criterion.
Actually, the rays seem to merely grow out to normal length so the abnormality really is inadequate membrane development. This deficiency can be characterized by referring to the percentage of inadequacy similar to the degree of spread in Half Moons. The ray extension might range from say 2-3 percent to 5 percent, all the way to 35-40 percent or more. The more extreme ones have what I like to call a 'Rooster' tail because of their resemblance to the tail feathers of a fighting cock. At the time of this writing I have not seen rulings passed by the IBC judging board or statements from breeders as to which, if any, of these variations constitutes the ideal Crown Tail. I trust this subject is being addressed and there will be guidelines of some sort in the near future.
Are There Half Moon Or Crown Tail Genes?
In my opinion the answer is no! Both traits exhibit continuous variation. Both also turn up in relatively small numbers in spawns. Both seem to nearly disappear in F1 hybridization with strains that do not 'carry' the traits. True breeding strains of either do not, to my knowledge, exist. They certainly are not traits that are inherited through the single gene, dominant-partial dominant-recessive (Mendelian) mode. They also don't really conform to the multiple factor or multigenic mode although that might come closer. So how can they be explained?
I believe these variants represent an extreme of some part of the normal range of variation of whichever genetic type they are. Another way to put it is that all the fish from a spawn are basically the same genetically and they only vary within the scope of possibility for their type. There doesn't need to be mutant genes for Half Moon or Crown Tail to provide for the types. I believe breeders have seen something desirable about these respective tail shapes and tried to, by selection, breed to enhance them. To some degree they have succeeded."
So basically, a fish could be an extreme on either end (Crowntail/No crowntail), or any graded level in between. Both of my veils have comb extentions.
i think its just semi normal
ill read it, sry about that 
