Bio geeks (or anyone else for that matter) check this out:

In other Hadith of the Holy Prophet (SAW), it is narrated
"When 42 nights have passed over the Nutfah, Allah sends an Angel to it, who shapes it and makes its ears, eyes, skin, flesh, and bones. Then he says, "Oh Lord is it male or female?"And your Lord decides what he wishes and then the angel records it.
It is interesting to note that the Angels ask Allah,"is it male or female?" Although the gender of the embryo is determined at fertilization the morphological characteristics of the male and female only begin to develop at the 7th week and visible at 9 weeks. The query noted by the Angels matches modern day observations.

Hmmm...does that mean we can still change our genes after fertilisation? Or this is how there would be confusion over the sex of some people? I dunnow seh.

Anyway, to know more abt stuffs related to this, click here:

http://www.research.com.pk/home/fmri/books/eng/creation-man/index.minhaj?id=5