I was born in the U.S., but I have all of my extended family on my mother's side in Thailand.  Though they do not know anything about my future employment, they never mentioned anything about strange-looking people asking about me or the U.S.  Since my BI has ended, I am assuming the agency did not check into my family there.

They did, however, ask during the poly how often I talk to my extended family and if any of them had any anti-U.S. views that I knew of.

opp:

They are close in terms of relationship (i.e., grandmother, aunts, uncles, 1st cousins, etc.), but unfortunately I have limited to no contact with them, outside of what my mother relays to me.

I assume this very limited contact is why they didn't persue further investigation.  I imagine if you are extremely close to foreign nationals and have recent contact with them, it would be a different story...

On a side note:  Just because the original BI may not have investigated your foreign family, that doesn't mean it still can't happen.  From what I understand the adjudicator has the power to launch further investigations where he/she sees fit.  Since I have been in adjudication for nearly 6 months, I guess I can't really say for sure that they aren't somehow checking my foreign contacts.