It's hard to know for certain.
Plants are not equally robust, so even the fact that some are fine and others are not is not necessarily proof that your environment is not at fautl. Double check for light pollution. Your methods (topping, pruning etc) can also cause such things.
If it's isolated and doesn't continue to pop more and more, i'd wager it's something you did or in the environment -- and, still possibly exacerbated by a predisposition in the gentics too. If it's happening all over and isn't just one wave of male bits growing, i'd wager it's a plant that naturally does it (or a really fucked environment with light pollution, lol). That's just a guess...
all you can do is make sure the things you do are not the cause and then go from there. You'll never know for certain if it was you or the plant, though over time you may recognize some trends that will make one or the other more likely.
Worry about what you can control and roll with the punches. Shit happens. Maybe, you got 2 shitty batches of seeds. HSC is reputable but certainly not infallible. Like th eother guy's commenton fastbuds.. i've grown 6-7 of their strains and never had a problem. Anecdote is mostly based on feelings and a small sample size.