Congrats on the not getting knocked up early! In my family at least, that appears to be a serious achievement!
The study had controls for that, and found that about 30-50% of the variance associated with the difference was probably genetic. Now that means culture and society still play a bigger role than genetics, but the genetic difference is obvious.
This is of course assuming the study was done correctly, and I haven't had time to read it to be sure.
I don't see in the article if this is published work, but as science reporting is generally crappy that's not surprising. If it hasn't been published, then it may not have been peer-reviewed yet, so the quality of the study is currently unknown.