What would cause plants to be male?

I have a a little problem thats been really getting on my nerves. Ive had several sucessful outdoor grows but every single indoor plant ive had has turned out male.

I have more than adaquate light, ventalation and have used several different brands and types of soil, as well as numerous techniques.. What the hell is going on? Does plant size affect sex in any way? because I usually switch to 12/12 after only a month and a half or 2 of veg (due to space restrictions)

Ive decided to give it another shot with a couple of orange crush seeds I got a few weeks back.

By the way, everything ive tried has been bagseed. Im a little hesitant or actually pay for seeds if this is gonna keep happening