No, while most boys' growth plates fuse by age 21, meaning significant height growth largely ceases, some may continue to grow slightly into their early twenties.
Understanding Growth Plate Closure
The primary factor determining height is the closure of growth plates (epiphyses) located at the ends of long bones. These plates are responsible for bone lengthening. Most boys' growth plates fuse by age 21. [This is supported by multiple sources](https://www.medicinenet.com/can_a_man_still_grow_at_24/article.htm, https://www.parents.com/kids/development/physical/when-do-boys-stop-growing/).
Variability in Growth Cessation
While 21 is a common age for growth plate closure, individual variation exists. Some boys may see continued, albeit minimal, growth into their mid-twenties. [This is acknowledged by several sources](https://www.quora.com/Do-males-stop-growing-at-18-or-21, https://www.healthline.com/health/do-guys-keep-growing-until-age-25). Factors like genetics, nutrition, and overall health play a role.
- Genetics: Family history influences growth patterns.
- Nutrition: Adequate nutrition during puberty is crucial for optimal growth.
- Health: Underlying health conditions can impact growth.
The notion that boys never stop growing is inaccurate and unsupported by scientific evidence. The Reddit post mentioning 15-foot-tall men is clearly a humorous exaggeration.
It's important to distinguish between height growth and overall physical development. Even after height growth ceases, individuals continue to develop muscle mass and body composition throughout their adult years.
