Young children today get an early exposure to sexual images through media, be it television, magazines, films or internet. Not only that they often come across the word 'sex' from everywhere and anywhere.
These images most certainly pique their imagination and they realize that there is something that they are not privy to, not yet. But their intuitive mind tells them that that is something that they should know or that is going to relate to them later in life.
When they understand that these images have something that is intimately related to their being on this planet, they are intrigued about sex and a kind of anxiety sweeps them.

Besides, at the age of 11 or 12, their bodies are undergoing certain changes which also add to their anxiety and curiosity. Near at 11 or 12 years of age, girls are reaching their puberty and boys can notice increase in their facial hair and they can sense an undercurrent of sexual, physical changes happening to them.
When 12-yearl Sandeep's childhood friend Deepali stopped playing with him one day, he asked his mother what the matter was. And he was quite shocked to learn that Deepali had started menstruating and he had a barrage of questions for his mom what it meant.

It is better that as parent you talk to them and decide how and what you are going to tell them. Since many children learn about sex through magazines and internet anyways, there is no point avoiding the issue. Instead of having half-baked knowledge it is better that they know it through you so that they can ask questions that are there on their minds.

This is very important to develop a healthy attitude towards sex in children. This is nothing to be embarrassed about and that sex is a beautiful aspect of life. Also they should be taught that there is a right age to do things.
So before their friends tell them misleading information or magazines just arouse their curiosity, it is better that they learn the correct information from you on sex.

You should talk to them in a way that they learn to become comfortable with their bodies and its many changes. Besides, girls and boys should not have any inferiority or superiority complex because of their gender.
Children should be strictly told to be careful and not to indulge in any kind of sexual experimentation under the influence of media.
Mothers should let their daughters know the right age to start wearing a brassiere. Values which do not look at woman only as sex objects should be inculcated in boys. Daughters should also be taught that they are more than mere reproductive being and beyond sex objects, contrary to what the media is constantly trying to emphasize.
Boys are most curious about 'masturbation' because they learn about it from somewhere or the other. It is important that fathers talk to them about it and give correct information.