" Androgens have diverse effects on hair in different body regions.[22] Effects vary from essentially nonexistent (e.g. on eye-lashes), weak (on temporal and suboccipital region hair), moderate (on extremity hair), or strong (on facial, parietal region, pubic, chest, and axillary hair). Androgens bind to receptors both in the cytoplasm and nuclei of dermal papilla cells and some cells of the sheaths of the follicle, but only if the hair is in anagen or telogen.[23,24] Two molecular forms of androgen receptors have been proposed: active (protein-monomer, 62 kDa) and inactive (protein-tetramer, with four subunits, total molecular weight 252 kDa). The monomer form has much greater affinity for androgens (dissociation constant for dihydrotestosterone is 2.9 nM)."
" Among all androgens, dermal papilla cells are most affected by 5- -dihydrotestosterone (5 -DHT). It is synthesized in these cells from testosterone under catalytic action of the enzyme 5- -reductase.[32] This enzyme exists in two forms (isoenzymes) - type I and type II .[33,34] 5- -dihydrotestosterone is further reduced to 3- -androstanediol which, after conjugation with glucuronic acid, is excreted in urine. Plasma and urine levels of 3- -androstanediol glucuronide are the most precise clinical indicators of the extent of testosterone transformation to 5- -DHT).[35] They are elevated in hirsute women."
"Insulin-like growth factor I (IGF-I) accelerates, in a concentration-dependent manner, growth of hair and hair follicles.[14] The actions of IGF-I are modulated by proteins produced in dermal papilla cells which bind IGF (insulin-like growth factor-binding proteins: IGFBPs); the exact mechanism of modulation has not yet been resolved.[15] However, it has been shown that IGFBP-3 (which is the most abundant IGFBP type in dermal papilla cells) forms a complex with free IGF-I to reduce the concentration of IGF-I available for stimulation of hair elongation and maintenance of the anagen phase.[16] Retinoids and glucocorticoids stimulate production of IGFBP-3 in dermal papilla cells. Insulin itself has the same effect as IGF-I; it has been observed that body hair in patients with hyperinsulinism has a male distribution pattern.[17,18] On the other hand, growth hormone (somatotropin) has no direct influence on follicle and hair growth."
So to put it simply... Some more than others