TELLING SMALL children how babies are made is the easiest bit. Unless you live in a box, pretty soon they'll have questions about sex abuse, AIDS, maybe prostitution or rape, and you wince at their loss of innocence.

And then they won't talk to you about sex at all - just when you want to know exactly what "getting off" means nowadays, and, well, have they done it?

Many parents would envy Niamh's open, no nonsense approach to sex education. "When they're eight or so, I tell them how babies are made. A bit later, I tell the girls - and the boys - about menstruation. Usually I'd pick a time like walking home from somewhere, I wouldn't sit them down formally.

"As they get a bit older, I talk to them about making love. I know they'll have sex before they get married, but I tell them to make sure their boyfriend/girlfriend has respect for them, and vice versa. I tell the boys to have respect, but I also tell the girls that a lot of boys will have sex with anyone - it's the truth. I tell them that sex is a gift, not given away lightly."

Niamh tries hard to remember what she was like when she was 17. She talks to her children about the dangers of drink and casual sex, the realities of getting pregnant and being a teenage mother. And she has promised them that when the time comes, she will go with them to the Well Woman clinic to arrange contraception.

She believes that her open attitude is possibly the best protection they can have against too early sexual activity (combined, of course, with normal parental vigilance).

This generation of parents - the thirty to fiftysomethings is much more concerned about children's sexual education than Irish parents were in the past, says Ruth Riddick education officer of the Irish Family Planning Association (IFPA). "But they don't always feel they're the best qualified to provide it, because they got no sex education themselves. Survey after survey shows parents want sex education in schools. But it's true that parents are the primary educators."

The truth is, as with so many parenting issues, the theory is easier than the practice. Good sex education theory is that you keep the lines of communication open, start sex-ed very young by giving simple, honest, age appropriate answers to children's questions. As the years go by, you keep on providing answers and information (because they do forget), raising the subject yourself should your children forget to do.

When they're teenagers, you are honest about stating your own attitudes and values about sex, without being moralistic or judgmental - a tricky enough balancing act.

The good news is that if you find ail this difficult, you are perfectly normal: Mary O'Conor, sex therapist with the Albany Clinic, says that parents should not - get too guilty - about what they're not saying.

"We all preach about keeping the lines of communication open, but the embarrassment is normal. There are boundaries between parents and teenagers talking about sex for example, if an explicit sex scene comes on telly while you're watching with your teenager, you can be as permissive as you want and still be uncomfortable."

IF YOU ARE that earnest parent whose children roll their eyes impatiently when you try to talk sex to them, take heart, O'Conor says. "Be honest, tell them your values, every so often, raise the topic, and just reassure them that you're there to talk and answer questions if they want to. Even if, probably, they won't."

Rid dick agrees that sex education is not easy, either for parents or teachers. But even if you squirm at the idea of talking about sex to your children, it is better to say so, to say "I am not comfortable talking about these intimate issues, but I'll do what I can," rather than to sidestep if.

Angela says she and her teenagers talk very openly about sex and sexual issues, but not in relation to what they do themselves the children would shy away from revealing anything personal.

Maureen has a good technique for dealing with embarrassment: she tries to talk about sex in the car, when eye contact can be avoided. Usually, she'll be reminded of something she wants to talk about by something in the news, and says she'll burble away, asking questions, and answering them herself if her teenage children simply fall mute.

Neither Maureen nor Angela expects that her children will wait until marriage for sex - but both expect them to be responsible. Maureen remembers vividly what it was like to be a teenager, and understands pretty well the kind of pressures they're under.

This is a key point, Riddick says. You shouldn't burden your children with your sexual history (they mostly really don't want to know), but you should try to remember what it was like to be full of raging hormones.

It's important, she adds, not to get fixated on factual information. It's more important to talk about feelings, values, and moral attitudes, to promote children's own self esteem. She recommends a trip to the "family health" section of any big bookshop for a selection of titles that deal with facts.

It seems that the queues here will mostly be women, for even though both parents may agonise, "it is still overwhelmingly mothers who take on the responsibility of sex education," says Riddick. But that's another story.