The debate between nurture vs nature is something we can all attest to thinking about. While yes there are studies out there that prove it is better to learn a second language at a younger age because that part of the brain is not fully developed allowing them to exercise it and learn two languages at the same time. My Spanish professor last year said her three year old goes to day care and speaks english all day then comes home and speaks Spanish to her and her husband about what they did. Although it is hard to determine how language develops it sure helps when the environment around the child is progressive.

A child's pronunciation of certain words can be influenced by their surroundings. Parents and environment can create an accent like southern or English.