Lesser Bantams in British Army WWI

What sorta conditions would be required for there to have been far fewer British young men during WWI who were undersize- even shorter than the mandated 5'2in/5'3in minimum height requirements- due to the effects of the Industrial Revolution and cramped living conditions and poor diet ? How could there not have been a situation during 1914-18 where Dominion soldiers from the colonies (esp Australia, NZ, Canada) were generally a few inches taller than their British counterparts ?

BTW, this is not a thread aimed at short ppl (lol).
 
Top