Why eyebrow growth stopped after it has specific length?
Activation of the mammalian gene Lhx2 leads to increased hair growth. Lhx2 is a transcription factor which regulates hair formation.

&quot;...length of the hair is determined by the duration of the growth phase; for example, the growth phase for scalp hair can proceed for a number of years, while the growth phase for eyebrows last a few months.&quot;

Other genes that have been associated with hair disorders include: FOXN1, ALX4, HOXC13, MBTPS2, VDR, CDH3, HR and ANTXR.