No, as far as we know Tom is Tom. I've been assuming Alexis's origin is going to go back to when Tom was being held captive by Karen. Although I do like the ideas that Lourdes or the deharnessing machine had something to do with it.
I like the idea that the machine had something to do with, but I have a feeling the point was more that Karan was looking for overlord replacements that were half alien and half human or something equally as silly.
I'm assuming little star child will be the key to stopping the Espheni once and for all. While that can be ho-hum obvious, it all depends all how it's handled. It can still be handles in an interesting manner.
The human resistance in V still needed the Red Dust, and in the ongoing series the star child suddenly a hot (she wasn't, she really wasn't, terrible casting, terrible.) Star-teen had bollocks all to do with the course of the new war after the Dust stopped working in extreme climates. I liked the Starchild on the 4400, and when she turned into a hot Starteen the casting found a very beautiful young woman to play the part, even if the script was all the hell over the place... But then 10 years later she takes her top off a lot in House of Lies when I'm too old to get excited about those sorts of things anymore.
Maybe both? Karen started and planned for the kid to be half alien, but the deharnessing machine altered the kid somehow so it isn't evil.