[adamc]

Thanks for the link! Hadn't heard of that, although I've seen similar reasoning in other contexts. (Basically, the most reasonable estimate, absent other data, is that you are at the mean -- so, for example, one could reasonably guess that half the people to ever be born have been born at present.)

[stevesimmons]

So some people have 4 testicles?

(assuming I'm average...)

[tomjakubowski]

I'm probably missing the point here but yes, in fact. https://en.wikipedia.org/wiki/Polyorchidism

A Rare Case of Polyorchidism: Four Testes: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4747319/