Which by the way makes no sense. I think they need to check their timelines. Was this like 10 years before the blackout (clearly, they went with young actors instead of Burke and whoever plays Monroe, like in the pilot)? This kid is only 11? The blackout happened 15 years ago? WTF?
No, the 11 year old mentioned was Aaron's wife's daughter, that made sense since Aaron left her 15 years ago, she hooked up with someone 3 years later and had a daughter.
All Emma told Monroe was that his son was away, not his age. But if you guess that Monroe and Miles were in the military for 10 year before the blackout and then add the 15 years, they kid would be around 25 or so. I have a feeling that Monroe's son might be someone that is right under his nose all along