Interesting Study: Testicle Size vs. Paternal Behavior

I know many of us think about gender roles and physiology. Here's a story about an interesting study which looks at how the size of a man's testicles might affect how he relates to his children.

http://www.bbc.co.uk/news/health-24016988

Spoiler: Men with smaller testicles, on average, take a more nurturing role in child rearing.