Many people focus on how much testosterone but what really matters is how well their body responds to androgenic hormones two people can have the same testosterone level but different results one might gain muscle and facial hair easily and look more masculine while the other sees little change the difference comes from how sensitive their androgen receptors are, androgen sensitivity is mostly determined by genetics specifically by your androgen receptor (AR) gene which sits on the X chromosome since men inherit their single X chromosome from their mother your androgen sensitivity is passed down from her side this means your father could be a hypermasculine terra chad with perfect bone structure and dense muscle but if your mother carries an AR gene with low receptor efficiency you can still end up looking like a wimp with weak androgen response the key detail in this gene is the CAG repeat length a shorter CAG repeats allow stronger receptor activation meaning androgens like testosterone and DHT bind more effectively and trigger a stronger response in the body, longer CAG repeats are very sub optimal they weaken this signal so even with high testosterone levels the body reacts less strongly
outside genetics local enzyme activity also plays a big role the enzyme 5α-reductase converts testosterone into dihydrotestosterone which is a very potent androgen that binds to androgenic sensitive tisues so a person with high 5α-reductase activity and short CAG repeats will respond much more powerfully to the same amount of testosterone than someone with low enzyme activity and long repeats
outside genetics local enzyme activity also plays a big role the enzyme 5α-reductase converts testosterone into dihydrotestosterone which is a very potent androgen that binds to androgenic sensitive tisues so a person with high 5α-reductase activity and short CAG repeats will respond much more powerfully to the same amount of testosterone than someone with low enzyme activity and long repeats
