Board Thread:New on Tokyo Ghoul Wiki/@comment-173.225.194.108-20160123222633/@comment-213.66.199.45-20160125055558

A ghoul can be born with the "kakuja gene" though...

Which mean that it has a potential from birth to develop a kakuja but it´s more like a seed and not a full on flower.

It needs care, nourishment and patience to sprout and grow into a kakuja after all.

In this case, it´s definitely confirmed since Eto inherited the "kakuja gene" from Yoshimura. They even got the same kakuja. (until she took it leaps and bounds beyond the level he stopped at.)