Well, I actually wouldn't recommend that. However, according to a study conducted by anthropologists at Emory University in Atlanta involving 70 local fathers ages 21 to 43, showed that fathers testicular volume and testosterone levels were inversely related to parental investment and testes volume was inversely correlated with nurturing-related brain activity when viewing pictures of their own child.
Which means the smaller your testes, the better your parenting skills.

http://www.latimes.com/science/sciencenow/la-sci-sn-men-smaller-testes-f...