If someone can't speak proper English by adulthood who is to blame?

If someone grows up in an English speaking country but has a poor grasp of English as an adult, where does the blame lie?
If someone cant speak proper English by adulthood who is to blame?
The school for not doing their job
Parents for being shit parents
Society
The person for being lazy or dumb
Select gender and age to cast your vote:
If someone can't speak proper English by adulthood who is to blame?
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