I can personally vouch for that theory that "she'll learn English anyway." My parents were both raised in the US and speak fluent English, but I was only spoken

I can personally vouch for that theory that "she'll learn English anyway." My parents were both raised in the US and speak fluent English, but I was only spoken to in Spanish. At the time I started school, English as a Second Language programs didn't exist and I nonetheless learned English in class without realizing it in probably a few months. As for learning both languages faster, I'm not entirely sure, but I only have one data point, so make of it what you will: my younger brother did not start speaking until a much older age than I did, but when he began, he spoke both languages at the same level a child would if he only knew one. (He had been spoken to in English and Spanish all along).