Autos different heights

I found that every time I have planted autos there is a difference in size of the plants of same variety. There are plants that grow a meter+ high and always one or two that only grow about a third of a meter high or less. Same conditions and feeding. I have grown several kinds over the years. Is this norm and does this sort of thing get weeded out after evolving the plant for a few years?

Just lift the other plants mate it will always happen not all plants grow and the same time, just lift them up so there the same high as the others and get the same amount of light I've had the same with 2 of my 6 autos lot smaller than the others