While talking with a certain medical student close to me, along with another friend of mine who just qualified as a doctor, I was inspired to have these thoughts:

Given that
1. Wearing tight briefs decreases your fertility
2. 'Elite' organizations (like the PAP or some schools) enforce an all-white dress code
3. You cannot wear any colourful underwear when wearing white trousers, or you'll look silly, and are thus forced to wear tight white briefs (boxer shorts don't come in white, as far as I know)

Thus it follows that the all-white dress code is at least partially responsible for a decline in fertility among the men who belong to these institutions? MM Lee believes that the 'elite' who belong to the aforementioned organizations should breed more, and bemoans the falling Singaporean birth rate, but perhaps the dress code he imposed on his own party has been a contributing factor.

In this light, it is hardly surprising that ACS and Chinese High boys have always been considered much more virile than students from some other institutions.