>>11613049Just think about it on the biochemical level — if there are two sequences, two molecules have to be made. They're being made from different versions of what's considered the same gene — variants of a gene are called alleles. You can think about it like a blueprint for a certain sized house. There are a bunch of different things I could add to the house, but it's still making a house, a thing with a specific function, and of a certain size.
Pick a random chromosome - chromosome 3, for example. Somewhere on that chromosome there is a gene, a specific site, where a protein that's important in determining nose shape is encoded in the DNA. You have two copies of chromosome 3. On one chromosome, you might have variant ACGT, and the other might have CATG. Both will likely get expressed. You have two versions of the same protein. For this protein X, you have protein X variant mom and protein X variant dad both floating around in the cell.
You can think of it as like a command in a computer program that's stored in a hard drive. They're all laid out in a specific order. But there are two hard drives — your mom's chromosome and your dad's chromosome. But both commands end up being run, and the way they work together determines what you look like.
There's a bunch of other stuff that could happen, but assuming the differences between the sequences found on each chromosome are only in the proper coding region of the DNA sequence, both proteins will be expressed.
