I have been wondering if followers gain perks as they level or not.

I will be starting a new character soon and want to use Aela as my follower.

Now as i use the unofficial Skyrim patch which changes unfortunately change Aela to use heavy armor rather than light armor (stupid as she is a thief class with sneak....), which in-turn makes her sneak skill useless........unless she gains sneak perks while levelling.
I did make myself a small mod which reverts the heavy/light change but I didnt save it when I reformatted my HD and cant be bothered to re-download the creation kit......unless they dont get perks...then i might


So does anyone know if followers gain perks as they level their skills?

If they gain any Perks, it would be in their areas of expertise.

Some followers can do silent roll, but I don't know if it's perk-related in their case. Might be.

Anyway, can't you use a console command to give Aela relevant sneak perks?