The Max Planck Institute concluded that the families are shrinking worldwide. A 65-year-old has an average of 45 living relatives today. In 2095, a 65-year-old will only have 25 living relatives. The decline in the Caribbean and South America will be the most. In Germany, Austria and Switzerland, the number of living relatives will fall to 14.
The number of cousins, cousins, nephews, and nieces will lose weight. There will be more grandparents and great grandparents.
The country with the largest family size will remain Zimbabwe.

Source

Diego Alburez-Guiterezz, Ivan Williams and Hal Casvell, Project of Human Kinship for All Countries, Proceedings of the National Academy of Sciences, Vol. 120, No. 52, December 26, 2023.