leglock

Im just interested to know peoples views on the limits to a natural physique.....do you think there is a limit to the size and strength gains its possible to make naturally and whether age is an issue....ive trained on and off for many years and can honestly say i have made very little gains in the last few years during which time i have taken it probably more seriously than as a younger man......now in my late thirties i am wondering whether there is simply a genetic limit to size/strength in regard to natural training and age....obviously if we just kept growing and growing in size and strength forever we would never fit through the door so....just wondered what yall felt ?