Yeah, I grew up in a small American town and my cousins were more like my siblings than my actual sister because they were the same age as me. We all fled that small town, so the next generation are all growing up not surrounded by extended family.
I think there are good and bad sides to it. It was nice to grow up surrounded by family with a strong sense of belonging. But my cousins' children are growing up knowing people from far more diverse backgrounds than I ever had access to, which is good for them in a different way.
Overall, I think the effects are probably neutral