I have experienced something like this.'cause I applied for US tourist visa 3 yrs back and i told the officer that i have sister there in US (has a GC) and the officer rejected my visa. His arguement was that i'll not comeback. but it's long back, I am sure things are different now. If you have your I20, I don't see any problem. But if I were in your place, I wouldn't say anything about relatives.