Testosterone
Male facial hair
In humans, visible secondary sex characteristics include enlarged breasts of females and facial hair and adam's apple on males.
Facial hair is really a secondary characteristics of males in response to the male hormone testosterone.
The two sex hormones are estrogen in females and testosterone in males. These produce what are called secondary sex characteristics. Breasts, menstrual cycles, enlarged sex organs,etc in females and facial hair, muscle mass, enlarged sex organs, etc in males
The hormone responsible for male facial hair and muscle development is testosterone. Testosterone is produced primarily in the testes and is responsible for the development and maintenance of secondary sexual characteristics in males, such as facial hair growth and increased muscle mass.
The primary male sexual characteristic is the ability to produce sperm (ejaculate), all other visible changes are secondary male sexual charcteristics. Things such as ... pubic hair growth, armpit hair, chest and body hair, facial hair, deepening of voice, growing taller and increase in muscles etc.
It means they not currently taking hormones. Hormones have the effect of giving TS women softer skin, more feminine facial shape, wider hips, developed breasts, etc. They give TS men facial hair, a more masculine shape, and, notably, a deeper voice. If the person is not taking hormones, they are either in the early stages of transition - before hormones have been prescribed, or they are transgendered rather than transsexual and have decided to forgo a full transition. They will remain showing the secondary sexual characteristics of their birth gender, and retain sexual potency (as hormones will often cause sterility or a complete inability to "perform").
Their voice breaks - that is secondary. Hair starts growing under the armpits. In addition facial hair starts to grow at puberty in a male.
Primary characteristics involve the organs for reproduction. Males have testicles, females uterus. Secondary characteristics involve traits characterized by hormonal changes such as the differences due to puberty. Examples include breasts, facial hair, the growth of pubic hair and underarm hair.
Secondary sexual characteristics. These are physical manifestations that develop during puberty, such as breast development in females, facial hair growth in males, and changes in body shape and voice pitch. These traits are not directly related to the reproductive organs but are influenced by sex hormones and indicate sexual maturity.
If a male begins to develop facial hair, it can typically infer that he is going through puberty. The growth of facial hair is a natural part of male maturation and signals the onset of secondary sexual characteristics.
Hormones and a razor