For one nothing about growth rate and plant sex is 100% across the board but in the 37 years I have grown, when I grew from regular seeds instead of feminized seeds often times males would grow faster than females. Often times they grew much faster.
As I said it is not something that is 100% across the board because the differences in strains and genetics so you cannot really rely on that to tell you what a plant is or is not because there can be any number of mitigating factors but if all is equal and you use regular beans and a plant or some plants are outpacing the others in the vegetative growth stage by a good bit it is at least likely it or they are males.
　
But the only way to be positive is to wait until you see pre-flowers. It was said you will have to put your plants into flower to find out but in many strains if you veg your plants long enough they will show their sex while still in the vegetative growth stage. Most people do not veg their plants that long so they believe a plant is incapable of showing its sex until they have been put into flower but that is not totally accurate.
　
Even in books written by some so-called professionals it will at times say plants will not show their sex until after the light cycle changes/is changed to a 12/12 cycle and that it can take up to two full weeks in a 12/12 light cycle before the hormones in plants that begin flowering will fully kick in and only then will the plants show their sex but they are also not totally accurate. Some strains are different from others.
　
Many, many, many, MANY times in my 37 years of growing my plants have shown their sex while still in the 18/6 light cycle so I know without any doubt that some strains can and will show their sex while still in the vegetative growth stage if you veg them long enough.
