Either I've missed it, or it was not explained: why is Lexi in Falling Skies a half-alien?
The only explanations I have are "just because", "due to the eye bug", and "because of something unmentioned that happened to Tom on the alien ship", but all of these seem weak and Googling didn't really help.
Addendum: Falling Skies wikia lists The Monk and Karen under her "family" as her DNA donors. However, the texts don't explain this and I still cannot place it in the timeline. Those two had access to Lexi after Karen captured her, but that only happened because Anne has already discovered Lexi's mixed DNA which made her escape the camp. Any thoughts are welcome.