Is the idea that you learn languages better by starting earlier really just a matter of reps?
For example I teach my daughter Spanish by speaking one hour a day. My daughter that I started at 2 will be better than my daughter I started at 14 not because of age but because the daughter at two gets a ton more reps? And that of both daughters got the same reps, the daughter at 14 would learn better?
Not only that, but the 14 year old will learn FASTER due to metalinguistic awareness. In other words, she already has her first language fully intact, more or less, and can use the concept of how languages work to learn the second language faster. She'll get concepts more quickly, understand the concept of root words, stems, prefixes and suffixes, parts of speech, and will learn grammatical structures more quickly.
Also I might add-- since you're on F12, you might have heard people talk about Mackenzie Dern and how her accent has changed through the years-- a lot of people think it's fake or affected. It's actually completely normal. Languages tend to interfere with each other, especially when it comes to phonetics. If two languages have vowel sounds that are similar but not exactly the same, whichever language is the language of greater exposure at the moment will bleed over into pronunciation of the other language, and vice versa. I'll give a personal example. My second language is Japanese. I didn't start learning it until I was 18, but I always had a knack for it, especially the pronunciation. The notorious screwup for Japanese people speaking English is mixing up of R and L. The Japanese sound is somewhere in between, and it takes a lot of exposure for Japanese speakers to be able to hear the difference (as an interesting aside, the best way to teach correct pronunciation is actually to teach the ability to HEAR the difference through a technique called minimal pairs; once a speaker can discriminate between hearing the the two sounds, pronunciation has a tendency to self correct).
BUT, it goes the other way as well. As a native speaker of English, I surprised the shit out of myself when, after living in Japan for a while, I would sometimes substitute R for L or L for R when speaking English. It's bizarre, and I would always get a laugh out of it. I don't use my Japanese much these days, but if I took a trip to Japan for a couple weeks or a month, or if I were exposed to a lot more Japanese, I'll start to do that again spontaneously in speech occasionally. It's a really weird phenomenon. It turns out that foreign accent, or even accent in one's native tongue, is a pretty fluid thing.
There's actually a cooking show, if you can find it on youtube, of this black lady from Louisiana that has been in England for 30 years or so, teaching Cajun cooking. She has the funniest accent. Not Louisiana, not British, but something in between. It's not that she's being fake, this is actually completely normal.