When you're over 18, it's something they really don't like you doing, and if you use a foreign passport as an adult they will probably never give you a clearance if you care about that.
I don't know if you are delusional, or just a liar, but I know plenty of foreign nationals with security clearances, some of whom have dual nationalities. Dual nationality is no bar to any Government job.
BTW, a programmer who is surprized when someone on here scams her username? What do you do at Amazon, get the coffee?