This is correct. Statistically, you are 50% each parent, but due to how recombination works in reality you will be a tiny bit biased in one direction. There is probably a paper that estimates the exact distribution of this bias, but I would have to find it.

Once the initial cell is formed from meiosis, every cell in your body will be derived from that genetic makeup. However, from that point on each new cell will accumulate mutations that differentiate it from its source cell. Your body is a complex mosaic of different mutations that accumulate over time. While it could be the case that one of those mutations make a variant that makes that region of the genome look like the other parent than it was derived from, this is very unlikely because the genome is very big relative to the amount of variation that exists in the human population.