geek, thanks for the explanation. That's fascinating stuff. Incidentally, my girls are nearly 4 years apart and I've been known to dress them alike. Hey, it's cute for pictures and special occasions. Apparently, my identical twin aunts absolutely loved dressing alike and believe it or not, were known to trick their teachers and school mates by switching places. I know that sounds incredibly hokey, but it was the '50's after all. Now my older daughter goes to school with a set of girl twins, and these two can't seem to put enough distance between them - they even requested to be put in separate classrooms this year. Go figure.
Oddly enough, I don't think I've ever seen a set of boy twins, but plenty of girl twins and boy-girl (I know those can't be identical, though). Is it more rare to have boy twins, I wonder?
ETA: Veronica, I missed your post - hope congratulations aren't premature. Home tests shouldn't give false positives, so I'm betting that you are indeed pregnant. I would definitely stay away from any cold medication before checking with your doctor. I was down with a terrible flu when pregnant with my second - horrible. If you're having problems breathing, though, I would seek medical attention sooner than Friday.