Final answer:
Juan's physical and behavioral characteristics could be attributed to high levels of testosterone, the male sex hormone responsible for male secondary sexual characteristics and a factor in certain aggressive behaviors.
Step-by-step explanation:
Juan's strong, muscular build and associated violent and aggressive tendencies could be attributed to high levels of the male sex hormone testosterone.
Testosterone is known for its role in developing secondary male characteristics such as muscle strength, facial hair, and a deep voice. It is also a key factor in behaviors typically associated with masculinity.
LibreTexts sources provide information on how testosterone and androstenedione, as primary male sex hormones or androgens, control the primary and secondary sexual characteristics in males.
The connection between testosterone and behavior is complex, but testosterone has been known to increase aggressiveness in some individuals.
Anabolic steroids, which are synthetic variations of testosterone, have been linked to short-term behavioral effects like extreme irritability and aggression, as well as a number of violent acts committed by people who had not shown violent tendencies prior to steroid use.