My friend just asked me: my son is 8, is it the right time to discuss sex topic with him?

I think you should've started talking about sex even before this age. The importance of discussing sex with your child is like building a bridge between the two of you: it can eliminate so many problems in the future. But if you haven't, that's definitely the time to start!

Important tips:

• First and foremost, do not wait until your child comes with a question. Initiate the conversation yourself. You always want to be one step ahead of a "school bus" - unwanted and unreliable source of information
• Even despite what they say, you still have to raise up the topic as often as you can, constantly: they might say they know and just be shy about it.
• Always talk about sex casually, as you talk about all other developmental matters: playing with peers, talking to a grandmother, cleaning up your toys. If adults don't make a great deal out of discussing it, the kids will know that sex is just one of the normal aspect of life.
• Always chose the right terms so that you can use them later. Not too
  scientific - no need to inform the child that male and female species need to perform a coitus in order to reproduce. Just avoid wee-wee and pee-pee type of words that creates an
  impression that genitals and sex should be hushed down under special words.
• Don't wait for your spouse to start: whoever is more comfortable talking about it, should start. Every family is different: in some families father is more comfortable discussing those topics both with girls and boys, in some - mothers take up the job. IT IS A MYTH that daddy should talk to his son and mommy to her daughter. The most important message is that your child can talk to you about EVERYTHING.
• Never make negative comments about sex.

At every stage your child is interested in a specific aspect of sexuality. Be ready to spill the information he is psychologically ready for. When a three year old asks where babies come from she is not interested in kamasutra positions.

If you talk to your toddler you can tell that babies are made by mommy and daddy.

When a three year old asks where do babies come from, you should explain that children come from a special place in mommy's tummy where the baby develops for nine months. To take the babies out, mommies usually go to the hospital and the doctor helps mommy to get her healthy baby. As a rule, three year olds are not asking for information how the baby got into mommies tummy. It's important to point out that mommy's tummy has a special place for the baby, so that your little one doesn't think that women swallow babies for breakfast.

Four to five year old would want to know the extended version of this information. They know that Mom and Dad have to get married, or get together (whatever you are comfortable with). Daddy has the special cells, sperm that come from his penis. And inside mommies's body there is a special place, little egg ovaries, where women's special cells (eggs) are formed. If mommy's and daddy's cells get together, they'll form one cell that will grow into a baby.

Seven to eight year old is probably ready for the additional information on actual cell mixing up into a baby-cocktail. To make a baby man and woman need to get together and they will have an intercourse. During the intercourse the man puts his penis into a vagina to bring his sperm to woman's egg.

You can start discussing planned and unplanned sex with your eleven year old. Preteens years is the right time to tell your child about condoms and other methods of birth control. And again, always refrain from any negative comments about sex: even a slightest hint would immediately turn your child away from discussing it with you ever again.