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The first two results are in. Although the 37 markers are off by 8, with the exception of DYS# 391, all of the markers that are off are "fast-movers" (they mutate faster than the
others).
Cullivan is not a very common surname; it's about a quarter of the way from the bottom of the list of frequent surnames, so the similar results plus the improbability of having similar results and NOT being related means that these two individuals are related. The harder part is when.
Eileen Krause at FTDNA ran the results through their "Time to Most Recent Common Ancestor" prediction calculator, extending the calculation to 40 generations. For ease of calculating, they count a generation as about 25 years, so 40 generations would be 1000 years. Here is the result of the computation:
100 years - 0.02%
200 years - 0.93%
300 years - 6.45%
400 years - 19.52%
500 years - 38.00%
600 years - 57.01%
700 years - 72.80%
800 years - 84.06%
900 years - 91.24%
1000 years - 95.43%
She writes:
The percentages are very small at first; it is very unlikely that these two individuals share a common ancestor within the last 200 years. They have a 6% chance of sharing a common ancestor within about 300 years, meaning that in cases in which we see differences between two individuals on these markers, we would expect about one in twenty pairs to be related within 300 years. At 400 years we start to get to significant numbers; 1 in 5 pairs could be expected to be related.
The biggest growth from measuring point to point is between 400 years and 700 years, where the percent increases by 15-20% for each period of 100 years. This is your likeliest time frame; in about one half of pairs with this result we would expect to see a common ancestor in this time period. There is still the possibility that the common ancestor is more distant, but considering the time period in which many surnames were established, 400-700 years is a good range to work with. In generations, this would be about 16-28 generations ago (the father of the participant counts as generation #1).
Genealogical records are likely to be limited from that time period or even sooner than that time period, so you may not want to look for the genealogical connection just yet. The thing that would help you most at this point would be to test other Cullivans and find one that fits somewhere in between. If you can find someone who is more closely related to one of these two individuals and locate that more recent common ancestor, it will help you to springboard backwards along the path to the older common ancestor.
others).
Cullivan is not a very common surname; it's about a quarter of the way from the bottom of the list of frequent surnames, so the similar results plus the improbability of having similar results and NOT being related means that these two individuals are related. The harder part is when.
Eileen Krause at FTDNA ran the results through their "Time to Most Recent Common Ancestor" prediction calculator, extending the calculation to 40 generations. For ease of calculating, they count a generation as about 25 years, so 40 generations would be 1000 years. Here is the result of the computation:
100 years - 0.02%
200 years - 0.93%
300 years - 6.45%
400 years - 19.52%
500 years - 38.00%
600 years - 57.01%
700 years - 72.80%
800 years - 84.06%
900 years - 91.24%
1000 years - 95.43%
She writes:
The percentages are very small at first; it is very unlikely that these two individuals share a common ancestor within the last 200 years. They have a 6% chance of sharing a common ancestor within about 300 years, meaning that in cases in which we see differences between two individuals on these markers, we would expect about one in twenty pairs to be related within 300 years. At 400 years we start to get to significant numbers; 1 in 5 pairs could be expected to be related.
The biggest growth from measuring point to point is between 400 years and 700 years, where the percent increases by 15-20% for each period of 100 years. This is your likeliest time frame; in about one half of pairs with this result we would expect to see a common ancestor in this time period. There is still the possibility that the common ancestor is more distant, but considering the time period in which many surnames were established, 400-700 years is a good range to work with. In generations, this would be about 16-28 generations ago (the father of the participant counts as generation #1).
Genealogical records are likely to be limited from that time period or even sooner than that time period, so you may not want to look for the genealogical connection just yet. The thing that would help you most at this point would be to test other Cullivans and find one that fits somewhere in between. If you can find someone who is more closely related to one of these two individuals and locate that more recent common ancestor, it will help you to springboard backwards along the path to the older common ancestor.