Finding gender early in pregnancy.

Today I had my fetal testing sonogram. I'm measuring 13 weeks and everything looks great. The tech showed me a shot of the rump/legs and I saw was definitely looked like a penis. This is my second and it looked identical to the way my sono with my son looked. My question is how many of you found out the gender that early in your pregnancy? Is it too early to tell. Someone told me that males and females look very similar genital wise until about 15-16 weeks. Has anyone  speculated about gender at your 13 week sono and was it accurate as to what you were really having?