For those curious, here's the logic that went into the calculation:
In "Blood Rites," we learn that Murphy's youngest sister, Lisa, is a month short of 21. This book takes place in the late Autumn of 4 ASF.
We know Collin Murphy committed suicide when Karrin was 11, so Karrin can be a maximum of 12 years older than Lisa (in the case that he died before Lisa was born, but after she was conceived).
Therefore, in 4 ASF, Karrin is a maximum of 33 years old, or a maximum of 31 at the time of "Summer Knight."
In Summer Knight (2 ASF), Murphy's first husband's obituary states he was 41 years old. Therefore, there is a minimum of ten years' difference between the two of them.
Murphy herself says she was 17 when she and Gregory Taggart were married.
Now of course, this is assuming the far outside possibilities in age. It's more likely that there's 10 or 11 years' difference in age between Karrin and Lisa. The difference can't be too small, as Murphy needs to be old enough to have attained her rank. With 29 as the upper limit in "Storm Front," I'm guessing 27 as a lower limit.
I'm puzzled as to where I got 13 as the age difference between Karrin and Gregory. Eleven or twelve is far more likely, though I don't dismiss 13 as a possibility.
