Parents “blame” their children for bad behaviour, but they know that the child isn’t intentionally doing evil - the child did something because it felt good at the time. The parent’s job is to make that kind of behaviour not feel good, so that the child doesn’t choose to repeat it - which is why there is punishment before the age of seven, even though the child didn’t really intend anything evil by his bad behaviour.
Children under the age of seven are certainly capable of doing things that their elders don’t like them to do, but a child under the age of seven isn’t thinking, “I’d like to really upset my mother - I think I’ll do this.” No. The child is usually actually thinking, “Mom isn’t looking, so she won’t be upset, and it will be okay.” The child isn’t capable of realizing that some things are bad in and of themselves, no matter who’s looking or not looking. That’s why they need to be taught.
(1) Children can be totally lacking in moral responsibility in that they have no will or intellect that is actually operating. In this case they would be like those in vegetative states or perhaps like automatons. Or it is possible that they lack one or the other part of responsibility in which case they would be like the retarded. According to what you wrote, obviously children cannot be vegetative.
(2) However problems still arise regarding the age of reason and what is described in the quoted post. Firstly, the child needs “to be taught”. So in that case they must be more than automata. They must clearly have the ability to know. In that case, again they have the ability to intend, for to learn actually is to apply (that is, to intend) the intellect to one’s imaginings in such a way that one can classify data under some quality or predicate or species. But also, if children could not know, then it is absurd for people to try and educate children before the age of 7. In that case pre-k and kindergarden is a total waste and children actually don’t know math until they are 7.
(3) Secondly, you say “thinking”. But a thinking person has an active mind and as such, he can be convinced of different and opposing ideas. So it is contingent that children think that “i’ll do this because mom won’t be upset” and not true that all the time, children think that things are good or bad only because of incidental reasons.
(4) Thirdly, if parents don’t really blame children, then parents are only speaking metaphorically or poetically when they say “you are naughty”. But I doubt that most parents are merely speaking in similes or metaphors. Indeed, saying “play nice” would also be mere metaphor like if we call an animal “intelligent”.
(5) Fourthly you said “choose”. Now a child supposedly does not choose in the full sense of the word for he does not have either intention or knowledge. So then it is in vain for parents to correct their children through punishments since the child does not even begin to become “corrected” (except perhaps metaphorically) unless it has full knowledge and intent. For it is admitted that children have no responsibility and so, one cannot correct that which is not even morally responsible for anything. Indeed, such would not even be punishments but mere “conditioning”. Punishment would only apply to people 7 and up. Of course one could say that parenting very young people is just conditioning and only conditioning but is that what you really mean to say? If so, then why are children praised for making good friends before they are 7 and why are children supposed to learn reading and basic counting before they are 7? All this praise then is just fake praise and the children didn’t even learn anything probably. These conclusions seem absurd though.
I completely agree with this!
Seven years old sounds about right for most people. 
Most will keep on growing up in all ways. 