> ~47 million Americans aren’t native English speakers having immigrated from a non English speaking country.
Your link says 46M total which includes native speakers. So it does not state how many non-native speakers. (not that it would matter as most would be proficient english speakers, just pointing out you're exagerating and your numbers are wrong)
The question of your native language is answered long before any of what you’re talking about here. A 20 year old isn’t time traveling to have different parents when they take an exam.