I don't get how evolution could be wrong.

Bear with me.

Offspring have somewhat different genotypes than parents unless the offspring is a precise genetic clone right?

Genotypes result in phenotypes (with environmental input), some of which may have probabilistic advantages depending on environment, increasing the odds of that genotype getting passed down (with some changes as per the above statement).

So it seems like the only way evolution could be false would be if there were limits on the extend to which a genotype could be altered over time. But is there any evidence that there is such a limit? If the DNA is different, one molecule at a time over time, then eventually you would have a completely different phenotype. How could evolution not be the case if theres no limits on the extent to which a genotype can change? And I'm not aware of a shred of evidence that suggests that at some point genotype changes hit a wall and can't change any further.