DNA testing

I live in Wisconsin and my question involves my son.
He was named as a potential father to the baby of a 17 year old girl. The girl also had sex with one or two other young males around the same time, but she believed that my son was the father because of the birth date of the baby (Mar 5), which corresponds to the time she was having sex with my son. Yes, my son did have sex with her about the time of conception, but according to the blood type of all three, (he's O-, mom's O+, baby's B+) he should be ruled out as father, since the only type that can be produced by two O parents is an O baby. The young girl has since admitted that my son may not be the father of the baby, but since her parents are fighting for custody of the baby, the baby has been assigned a guardian ad litem, who wants to do DNA testing on my son, despite the above evidence. The blood types of all three are absolutely accurate, and one of the other males has a more compatible blood type for the baby. The guardian ad litem knows this but insists on pursuing my son as the father. Will the court accept the blood types as evidence that my son is not the father? Does my son have the right to refuse to do the DNA, because the guardian ad litem is asking for him to pay half the fee up front, and there is a more likely candidate for the father?

If you have such a strong feeling that is not your sons child based on the blood types I would recommend that you do a DNA test if your son refuses to take the DNA test it is considered by the courts an admission that he is the father. Look at it this way your son has a chance to take a DNA test Some men would love to take one and the courts won't grant one to be done. Which is cheaper about 150$ for his half of the DNA test or thousands of dollars for child support for the next 18yrs. I will let you do the math. My personal opinion? Do the DNA test and settle the issue once and for all, and ask your son to be more careful in the future so he will not end up in another situation like this.