If the soil is poor or if the nutrition level is low, which can cause bad genetics,then you probably will see more spikes.
Poor soil cannot cause bad genetics. Only bad genetics can cause bad genetics.
A deer herd living in habitat that is so poor that bucks remain spikes past thier first year needs a lot of help.
How do you KNOW they were 2.5 year old spikes? Were they teeth aged by a biologist?