I did a test on that theory some years ago. I also heard that less light=more females, so I went out and gave it a test, here is what we did.

We germed 20seeds, all from the same pack. We decided we will put 10seeds under 18/6, and 10 seeds under 24/0. We vegged them, then turned into flowering. From the 18/6 seeds, we got 7 of 10 females, great results. For the 24/0 run, we got only 3 of 10 females.

I don't know if that helps any. I use 18/6 always, so far I'm on my 3rd female in a row(from seed). Before I was using 24/0 and I got 4 males in a row, then I switched to 18/6, now I'm getting more females than males. Peace.