I've written about Parent's Day here before, but to refresh the memory, Language Stars periodically invites parents to attend the Kid's only classes. While there we pretend to be 3 year olds and participate in the exercises, while our children try really hard to impress us. It's rather adorable, even though Leilani wasn't doing a good job of paying attention.
About two thirds of the way through the class Reena Nair (the director of this location) pulled the parent's out and gave us progress reports on our children. Leilani is doing great, of course, and then she talked to us about myths of language development. One myth that seemed to be believed amongst some of the parents was that learning a second language would stunt growth in the first or primary language. The belief in this myth, even amongst parents who are teaching their children a new language, is unfortunate and had consequences for our family.
Our oldest boy, Anthony, has a high-frequency hearing loss. It sounds like a disability, but it really just means he shouldn't sit in the back of a classroom. As a small child the doctor told his mother to speak to him in only one language, claiming that the two languages would stunt his development, so they should really only speak English. This was a crock, and to this day I wonder if the doctor just didn't want another Spanish speaker in the world. Unfortunately now 21 Anthony speaks very little Spanish, an obviously useful skill, despite occasionally having an accent in his English reflecting his parent's.
The point, which I have likely belabored, is that it's never a bad thing to learn something. Would you refrain from teaching a child addition and subtraction because one might stunt the other? Or avoid Science and Literature at the same time? The notion is silly. A child's brain is built for absorbing language, take advantage and get them learning as much as possible.