My take on the Cardassian chest chufa, like Natima Lang has-
It is one of those quirks in genetics, like humans having a sixth finger or clef chin, is a dominant trait but is also very rare. Gender has nothing to do with the odds. It's less frowned upon for females to have and display theirs.
A small hint might be visible at birth but at puberty it would appear with other ridges. Most, especially those headed for the military and government, would have the ridges removed before anyone outside of the family and the Obsidian Order found out.
If there is a fad for it then high status females might decorate theirs or even get surgery to have one made.
Garak has one, the ridges were removed when he was in the order, a time came on the station where he had Dr Bashir put them back.
Dr Bashir might have figured out Enabrin Tain was Garak's father in the prison camp because Tain also has a chest chufa.
Therefore all of Garak's children would have chest chufas.