Research has been done
Much of the previous research has focuses on parents teaching themselves and their children a second language. Christine Galbreath Jernigan, Ph.D. Foreign Language Education, shares a quick summary of research she has contributed this far:
In 2001, I began an ethnographic study of parents who are teaching their children a second language. The study includes Learn from Other Parents interviews with and observations of over 80 families, extensive reading and writing on published accounts of parents or other researchers in this area, and my own day-to-day challenges and successes raising my children to speak Portuguese. Each time I publish an article or give a paper on this work, it appears that this type of teaching is not so rare and that more parents would try teaching their child a second language if they better knew how.
I have been researching bilingualism for over a decade. Much of what is on this Wiki at present reflects my own research in the area of children's bilingualism. I have focused on parents teaching their child a second language, meaning a parent is teaching a language he/she has learned later in life. I also have two young children I am raising to speak Portuguese, a language I learned in my twenties and am still learning. I would love to have your input.