Fiona, the sperm is boy or girl sperm, so its from the very "point of impact" that the sex is determined! LOL
Der Fletch! LOL I may be pg but I did know that.

I think Ryn kinda cleared it up for me

As for boy/girl, yes, your genetics are "point of impact" for boy/girl, but for the first trimester the baby doesn't have a penis, that doesn't start to grow until about 12 weeks, so all 1st trimester babies look like girls, but have the correct genetics and hormones for what they will be later.
Thats what I meant, I wasn't sure if seems there isn't the penis etc before 12 weeks, would there still be the hormones to have an affect on how you feel. But Yes I guess if the hormones are there from the start then it would, if it does.