sexing guinea pigs

Question
I am having all sorts of trouble sexing baby guinea pig. They are all out of the mothers cage and are exactly 4 weeks old. 3 of the 4 I noticed something red hang down while I was looking from the back side of them. After that, the guinea pig cleaned what looked like male geitalia. I am almost certain. When I put 2 of the 3 together, one mounted or tried to, one of the guinea pigs I swore was a male. Could I have made a mistake? I am giving 3 of the babies away, and I want to be certain of the sexes. I also don't want them to have the same problem I did. Bring an already pregnant guinea pig home. ps The red "thing" that I saw was maybe 1.5 inches or so. Thats why I was shocked when I saw I could be mistake.

Answer
Walter

Thank you for your questions!

I have the PERFECT website for you to look at. It contains well descriptvie information AND pictures that are extremely helpful!

http://cavyspirit.com/sexing.htm

The red "thing" most likely is the embilical cord still attatched.

Best of luck!

Amy