Language acquisition in optimality theory

In optimality theory (OT) the essence of both language learning in general (learnability) and language acquisition (the actual development children go through) entails the ranking of constraints from an initial state of the grammar to the language-specific ranking of the target grammar. This is the common denominator in all OT studies on language acquisition and learning. There are many unsettled issues, however. Are the constraints innate or do they emerge during acquisition (nature-nurture)? And if they emerge, where do they come from? What is the initial state? Does the (re)ranking of constraints only involve the demotion of markedness constraints, the promotion of faithfulness constraints, or can it be achieved by both the demotion and the promotion of constraints? Another issue is whether comprehension and production are mediated by the same grammar or whether there is one grammar for comprehension and another for pro!