It effects in a few ways, but the easy answer is that solar radiation and random error in the DNA coping during meiosis causes mutations in the DNA of the germ cells. The more complicated answer will take quite a bit of background in how meiosis occurs, understanding telomeres, DNA transcriptase, the cellular skeleton, and the division of organelles during that process. Before we try and get into that, are you cool with the idea that during the DNA copy process (unzip the helix, make complimentary new strand of nucleotides (AATACG is used to generate a new TTATGC strand)), the resulting DNA copy may have errors in it, and these error can be either due to environmental factors such as radiation interfering with the copy process, or just a simple error in the bonding process? As for Lamarck, when faced with the newly discovered fossils being uncovered from around the world, it was becoming evident that creatures had existed in the past which were no longer around. This was a huge problem not only for western theology, which presumed that God had created everything perfectly and thus the idea of extinction was outlandish, but also for science which was still heavily based on christian dogma in many areas. The apparent extinction of a few modern species like the Dodo added to the confusion - if God was actively providing things for man, and creation was perfect, how can a species disappear? Fossilization and geology (plate tectonics, substance, etc) were still emerging fields, and so the context of the fossils wasn't quite figured out yet. We just knew that there were leg bones being discovered which were twice the size of any living animal. We were also finding fossils which looked like mid-way points between those extinct creatures and modern forms, suggesting that these bones weren't just evidence of a prior creation which God had wiped out completely before starting the current world. Evolution was a pretty mainstream view by then, but the HOW of evolution was still being figured out. Lamarck's idea was among the earlier concepts that suggested natural means for these transitionary fossils; suggesting that creatures changed over time due to environmental effects on the adult body being passed on to offspring. This suggested clearly incorrect predictions, such as the giraffe example, or things like dogs with cropped ears would give birth to offspring with pre-cropped ears. This doesn't happen, and Lamarck's hypothesis was discarded pretty quickly. I understood it to mean that the faster a species reproduces, the faster mutations will propegate through the population. In that case, we need to look at punnett squares. The dominant/recessive nature of gene pairs, and the fact that most phenotype traits aren't encoded by single genes means that expressing mutations tends to be very complicated. But in general, the basic pattern of inheritence can be simplified down to a Monohybrid Cross; I think that's what you're referring to when you say that there is a 50% chance of passing on a gene. This 50% only applies in individuals that have two copies of a gene (one per chromosome copy), one of which has a mutation either through a DNA copy error or through inheritence from a parent, and there exists a 50% chance that a given germ cell will contain the normal gene or the mutated version. http://en.wikipedia.org/wiki/Punnett_square I understand your fear that people may be hiding behind terminology, but what happens when a topic is so complicated that the time spent re-defining words would take days if not years? How much time will be lost to re-inventing the wheel every time a new person enters the field? My error, then If you've rejected the idea, and you think it's unlikely already, can you honestly say you are being whoely objective? Again, my error. If accumulation of traits is possible, and each repetition of the experiment without a mutation leaves the likelihoods of the next round identical, BUT a tiny fraction of of repetitions of the experiment with a mutation increases (very slightly) the likelihoods of the next round in favor of the continuance of the mutation, why would it not be inevitable? This is a fairly insulting statement to those people. If you are asking for fair treatment, and considering yourself not prejudiced even though you already claim that evolution in unlikely, how is calling others badly prejudiced showing any respect? \ It is possible that some have judged you based on your personal rejection of evolution. From reading along, others would likely that the content of the arguments you have made against evolution are the problem. I don't know if personal character has played into their feelings on the matter, but I personally don't think it should. Personal character should play into judgment of the person, and the decision to continue a conversation or not, but it doesn't play into science. I may not like jerks, but if they have good ideas that can be shown to match the available evidence effectively, then they have good ideas. *shrug* I hope we can keep making progress, both in evolution, and possibly in you sharing your ideas (possibly in a different thread first to hash them out, then back here to more directly address them in the light of modern evolutionary theory). If your rejection of evolution is not theological but technical, I bet it would make an interesting discussion on its own.