Quote:
Originally Posted by FlDebra 
Say what? I have no idea how a vestigial tail in humans could possibly equate to a parti-carrier label on a yorkshire terrier. How about sticking to valid references that might contribute to the substance of this thread? Everyone is free to post any thought that pops into their head, but so much better if we list valid references that people can really use to make some sense of the subject at hand. There is no substantiative value to off-the-wall genetics anomalies that happen with such rarity as to be void of comparison. Not to mention a completely different genetic concept is the culprit.
All humans have tails (it is not the act of a recessive gene) during a part of their embryonic development. Most are absorbed by the immune system and only the coccyx (tailbone) remains. But VERY, VERY few (23 since 1884 --over a hundred years) may have a vestigial tail which is not fully absorbed prior to birth. Not the same as white color occuring spontaneously or otherwise. No matter if you are speaking to the tailbone, the tail in embrionic development or the congenital birth defect of a tail structure..... it still is not a valid comparison. When a child is born with this tail structure it is because the normal inactivation has not occured. The white color showing up is due to the recessive gene in both dam and sire joining in the same pup. Not the same genetic action at all. References say this residual tail is NOT familial -- instead "the inheritance of the tail structure is unnecessary since the developmental system has been inherited but is normally inactivated in humans." In other words everyone inherits the tail -- some inactivation mechanism just do not work quite right -- but again -- happens so very seldom! There is no such "inactivation mechanism" to thwart the "white" in all yorkies. It just does not compare at all.
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Thanks for taking that one on. I just decided to ignore the tail part of her quote and reply to the "what makes them a carrier" part.