I'm not aware of any immigrants in my family tree, but I'm only aware of my ancestry two generations back, so I can't answer the poll accurately without additional research. It isn't really worth my time to do that, so I'm not going to answer the poll.
Assuming I'm not a rare exception, the way your poll is worded will therefore be biased toward recent immigrants and people who know a lot about their family tree. Without knowing how much this bias is, there's not a whole lot you can conclude from the results.
You may want to setup an additional poll, such as:
* I am an immigrant
* At least one of my parents was an immigrant
* At least one of my grandparents was an immigrant
My guess is that more people could answer that poll than your current one, and you'd therefore get less bias.