AFP test, Are the things they test for genetic?
So I'm 18w2days today. I know I've posted a lot of questions but my I am just curious, because this is my first pregnancy. I went in for my Dr. Apt and I was offered the AFP test, the dr explained that it was checking for Neuro Tube Defects, and Down syndrome, and things, but my question is-- without any history of it in my family, what are my chances I could be affected? I know everyone is different and every pregnancy is, but I am paranoid at something going wrong. I don't get my results for a week, and I have been stressing about it to the max. If anyone could please shed some light on this subject for me, anything you may know would be great, Thank you.
Also, I'm 19 years old. Neither myself or my boyfriend has a family history including either if thse birth defects.