bb.com members are just extremely naive
they think you can get 17-18" lean arms naturally with dedication and hard work
using a number of an arm measurement to determine if someone is natural or not is ridiculous.
My friend is shredded and has 19+ inch arms, been training for eons and YES 100 PERCENT NATURAL, HOW? EASY, he is 6 foot 9 and his arms in a picture look like tooth pics.
Someone 6 foot can have 18 arms naturally no problem, 17.5 on Kyomo is possible naturally, not 100 percent sure if he is but I can believe that, very close to natural limitations though.