What do you look for when they are 1 week olds? I had a buyer here yesterday wanting girls and since I don't vent sex she decided to just take the smaller ones. Well... they hatched over a couple of days so that could be the size differenceYou need to know what to look for but it's easier when there's multiple to compare. I can usually. ..about 98% of the time tell at hatch. The boys are so much bigger, then by week 2 its very obvious. ..granted there's the 2% that you are constantly wondering then it sure enough is a drake!!