According to Wikipedia: [url=http://en.wikipedia.org/wiki/Evey_Hammond#Film_portrayal][quote]In the film, she has an older brother who is killed by a virus that was secretly developed from the experiments on V and other inmates at Lark Hill.[/quote][/url] So there are a few problems with your theory.

[quote][b]Posted by:[/b] DynamicVamp SPOILER!!! I am going to put it bluntly, then back it up with evidence. I believe Evey is V's sister. Now to back it up, at one point in the movie, on their way to arrest Evey, a few Fingermen said her parents were detained and her brother was sent to ST. MARY'S (or something like that). Incidentally, the same thing happened to V. Earlier in the movie, when V first meets Evey, he remarks upon her name and mentions coincidence. Why? Obviously the name is very familiar. V even says multiple times throughout the movie things that were said by Evey's family. The only problem I have with this is that later in the movie the relationship seems more... romantic.[/quote] i think the last part of your post sort of debunks it. it may have been just a coincidence since the writers put all sorts of references to the letter "V" in the movie and comic.

V EV Coincidence?