Having seen tons of white and Hispanic misbehaving kids I don’t agree. If anything black children are better behaved at that age when their mamas can still exert control over them ... IME.
If we are going to generalize, in my experience the spectrum goes Asian, Black, White, Hispanic with Hispanic kids being the worst behaved overall .... at this young age.
As far as I can tell black kids are the worst behaved at every age and most people will agree with that.