A survey reported in the 11 March issue of The Weekly Genealogist, by American Ancestors, found that 7% of respondents had at least one parent who relocated due to climate/weather issues.
Assuming the statistic applies across generations, what is the likelihood that at least one ancestor relocated due to weather/climate issues?
| Generations (n) | Total Ancestors (N) |
Probability of Having at Least One Weather or Climate Migrant Ancestor
|
| 1 (Parents) | 2 | 7.00% |
| 2 (Grandparents) | 6 | 19.56% |
| 3 (G-Grandparents) | 14 | 39.83% |
| 4 (GG-Grandparents) | 30 | 66.33% |
| 5 (GGG-Grandparents) | 62 | 89.46% |
| 6 (4G-Grandparents) | 126 | 98.97% |
| 7 (5G-Grandparents) | 254 | 99.99% |
| 8 (6G-Grandparents) | 510 | ~100.00% |
As the weather will impact a nuclear family equally, if they move, all will move; it’s likely that many more than one will have moved. There’s an assumption that all ancestors in the tree are unique (no pedigree collapse).
In the American Ancestors survey, based on 3,355 responses, 40% reported not being aware of any of their ancestors relocating because of climate/weather.
Does that imply 60% were aware? If so, and considering the estimates in the table, it suggests that at about the G-Grandparent to GG-Grandparent level, people become unaware of the impact of climate and weather on their ancestors’ migration.
The survey was restricted to migration caused by climate or weather. Other impacts, including death, would need to be included to evaluate the importance for family history.