Before answering this question, we need to agree on terminology on the shore. What is adulthood? By what criterion are we to judge?

In psychology there is the concept of periodization of age. A lot of them are different, and there adulthood as a period that is clearly linked to the age and characterized by certain life tasks at this stage, the person has to decide. But I want to talk not about the age of periodization, and that characterizes a person as an adult regardless of age.

For me criteria of adulthood are as follows:

• People responsible for their actions.
• a Person interacts with the real world.
• a Person familiar with its borders.

Deploy these items in detail.

Adult person aware of its impact on the world around us. Not a magical effect with the iron throne with the help of telepathy, but in simple: everything he does (or doesn't, here inaction is also action) has its natural result. Adult a man thinks in advance, plans result. And faced with it, admits: Yes, my doing. That is, appropriates the authorship.

to Usurp authorship of your life is very important and useful skill. One has only to realize their authorship and to take responsibility, just difficult to remain in the position of the victim, for example. If the author of I blame I blame no one.

Children responsibility for their actions do not carry. They are impulsive, guided by your desires and need to explained to them the structure of the world where they are the authors of awarded responsibility. Otherwise, when you hit the table will blame the table. For three years is normal, and then gone.

the World is not a clearly arranged structure, verifiable. The world is chaos, unpredictable, incomprehensible. In principle, it is not always clear what to expect from tomorrow (forgive me, disturbing). Adult the person is ready to interact with what we have.

Every situation in life as a card game: cards, certain cards in hand, and we begin to act from this point with what we have. Taking the initial conditions of the problem, agreeing with them. A grown man going to play cards, the child will throw them away because he didn't like the deal. If you ever tried to play with the kids cards, chess or dominoes, you know what I'm talking about :)

Also, a grown man understands that this distribution only for this batch, the next batch of cards will be others, and he will again have to deal with it. In General, we can say that an adult is a person able to take life as it happens. And the question here is not about sacrificial passivity. We are talking about how to keep going towards their goal, based on the conditions in which a person is, and not one of those conditions that he would like to have, being thus in illusion.

People knowing about your boundaries and know how to handle them, can be considered an adult. The child often merges the boundaries of the other adult, and this is because the child can not take care of themselves fully and is forced to sacrifice autonomy for the sake of security. An adult can bring such victims, since it must be able itself to provide security: shelter, food, and more.

Thus, when faced with other people at the border, where the end of his interests and needs of the other, a grown man able to defend their need while the child simply surrenders.