ever have a plant not show sex?

I heard some plants never show sex, just grows and grows.... I find that very hard to believe. A friend has an Afghani he got as a freebie from Herbies and he swears it has been under 12/12 for 3 months and shows no sex.
I think I need new friends.

Proabley need a longer dark period 11 13 i had a western winds that did that a sativa

Either that are get a new timer