Acculturation is the process by which a person assimilates to a culture that is not their own. This culture will typically be the main one in the society they are in. They will do this by adopting the beliefs, customs and value of the culture they are assimilating to.
Babies learning how the alphabet will not fall under acculturation because the alphabet is a part of learning that all humans must go through so the baby is essentially learning their own culture not that of another.
