Puppies Growing to look like parents?

We bred our female Jack Rusell Terrier with our neighbors Jack Russell Terrier. She had 4 pups, all female. 2 looked like each other although they were the largest and smallest of the litter, and two looked almost like twins (but were not).

Both were very similar to the mother in coat, markings, and appearance. It was hard to tell them apart as puppies. Similar personalities too. Our female is wired haired, thick coat, predominantly one color, and the male was short haired, white with large brown spots. As these two ‘twins’ grew they continued to look the same.

When the time came to let the puppies go, our neighbor chose one of the twins, and we kept the other. We see our neighbors dog every day. After 1 year, she has grown to look very much like her father (who she lives with) away from looking like her ‘twin’ and mother. She still the predominantly same color coat, but most of the wire hair has smoothed out and she has a black top to here coat making her look very much like her father. Even her face has changed to look like him.

On the other hand. Our puppy has grown more and more to look like her mother, with thick rough coat. You can clearly see they a mother and daughter. Much more so, than you can tell the two ‘twins’ are sisters.

Well after the long description. The question. Is this just the natural genetics at work whilst they are growing up? Or. Are these puppies growing apart and looking like the parent they are living with. To me. It feels like the latter. But probably it’s a combination of both.

I’d love to here your thoughts about this.