When you carefully track the amount of time participants spend practicing the language, children don't perform better.
Kids are forced to speak the native language at school and get ~1 hour a day of grammar lessons. Just because a kid can explain a biological process doesn't mean they are "innately" better at grasping scientific concepts than adults. It just means we were working while they were in biology class.
Some of the "learn a language young" hype is driven by MRI studies that show kids who learn young process the second language in a different area of the brain than adults. But processing "centers" aren't in the same place from person to person, they float around.
For english speakers there is no economic benefit to learning a second language either. So (as long as you are a native english speaker) don't spend any additional resources teaching your kids a second language.