| MadSci Network: Genetics |
A vasectomy could in no way circumvent DNA testing. All a vasectomy does is prevent sperm cells from be transported by the vas deferens. The ejaculate would still contain the same amount of genetic material of the person due to cellular contamination of the seminal fluid (dead cells containing DNA would be carried out of the reproductive tract. Also the act of copulation (consensual or otherwise) would leave skin cells which contain genetic material.
Try the links in the MadSci Library for more information on Genetics.