The most scientifically accurate explanation for why you may not reach the height predicted by your DNA is:
The environment, like getting enough sleep, eating right, being around second-hand smoke, played a role in how my DNA was expressed.
While your DNA provides a blueprint for your potential height, various environmental factors and lifestyle choices during your growth years can influence how that genetic potential is expressed. Factors like nutrition, health, exercise, and exposure to toxins can all impact growth and development, leading to variations from genetic expectations.