Even your friends disagree with you Jenny, that is why Vade and RWNilla are already heading for the hills and starting to say that even duplicate genes are immediately helpful. Because they see that you are wrong and that Mendelian genetics is a great problem for evolution. Heck, even look at Andrew's post#1641 from your favorite place, the evo home, Talk Origins. It too is contradicting with what you are saying and agreeing with me. Let me explain this one more time in a different way, perhaps you will understand it better.
1. It is well established that every individual has two sets of chromosomes, not identical, but very similar, and which function pretty much the same.
2. It is well established that on reproduction only one half of those pairs of chromosomes is passed on by the father and another half by the mother, the progeny thus receiving two sets but only one from each parent.
3. It is obvious that a newly mutated gene will appear on only one of the two sets of chromosomes.
4. Since only one of the paired genes gets passed by each parent and there is only one copy in the individual with the mutation, the chances of his passing it on are one in 2.
Now here's why it cannot spread even through a small population. Let's say it is a small species with only 1000 individuals in it. In those 1000 individuals there are 2,000 copies of the gene which mutated. There are 1999 copies of the gene without the mutation and only one with the mutation. On the first generation, 1000 of those 2000 genes will dissappear. Each one of them has half a chance to survive (see 2). Now on the first reproduction the chances are that the you will get either 1000 non mutated genes or 999 non mutated and 1 mutated gene. So what we have here is essentially a coin flip. However, the mutated gene, in order to win and become fixed needs to keep winning coin flips. The chances of that are infinitesimal. Not impossible but infinitesimal.
In short, it is a problem of population genetics. As I said, Mendel turned natural selection on its head. He showed that organisms are very resistant to change and that the odds against it are humongous any way you look at it.
No Gore. Wrong again. What I wrote had nothing to do with Jenny. You were just being very obtuse ruling out any potential effect of a duplicated gene. Vade and I suggested several instances where duplicated genes can have an immediate beneficial effect. The xylose example is very easy to grasp. I also pointed out earlier how even neutral duplicates could persist being next to "good" genes.
Mendel was very lucky in that the genes which encoded for the phenotypic traits he was tracking showed independent assortment. However when genes are so close together on the same chromosome, they get passed on as if they were "one" gene. Imagine now the duplicate sitting right next to your "dominant" gene in your little pundit square.