Originally posted by: kappamaki
Oh my...
I never ever post because I'm so busy with school, but as a pre-med student this discussion is really irritating me. I'm not even going to bother explaining genetics with you guys, though a think a few of you have done a pretty good job of explaining the basics (others, though, are somewhat misguided).
I just wanted to point out a fallacy of one of your arguments. We don't know if the sharingan is a recessive trait. Just because it shows up in a minority of the Uchiha family doesn't make it reccessive. As an example: in my extended family, only a few people have brown eyes. The majority has blue eyes. Does that make brown eyes a recessive trait? No. It just means that, in this case, the recessive trait has proliferated itself enough to be found in the majority. This actually happens in a lot of families.
Similarly, in the Uchiha clan, only a few people have the sharingan. Does that make the sharingan a recessive trait? Not necessarily, although it is more likely. So you can't assume the sharingan is recessive or dominant.
Also, genes are actually a lot more complicated than just dominant or recessive, and it is scientifically possible for two people bearing two recessive genes each to have a child that expresses the dominant trait, and vice versa. I'm not even going to began to get into this, though, since it would just take way too long.
Also, just out of my own personal curiousity, does any one know where in the manga does it say that only a few Uchihas have the sharingan? I must have missed it and would like to read it over, in case I also missed anything else.