In one case, I gave in to a 19-year-old guy and next morning found out that he was married or at least living with someone. After leaving my bed at midnight, he went home to hers! So what is it about these guys, Doc? Why do they behave to me in such a hurtful way?

A. Well, you have learned one simple truth and learned it in a really tough fashion. The truth is this: Most teenage boys cannot be depended on where sex is concerned. There are exceptions and I must admit that not all young guys are serial seducers.

Indeed, there are some male teenagers who have very little interest in sex and who don't particularly want to go to bed with anybody. However, a lot of guys under 20 are pretty driven by their male hormone.

That is really the key to the whole thing. In boys and adult men, the desire for sexual intercourse is largely due to the influence of the hormone testosterone. This chemical runs through a young man's bloodstream and makes him want to have sex with girls. That is a powerful drive. American researchers have calculated that the average male teenager has around four orgasms per week. And some of them would like a lot more than that.

Also, biologists say many males are conditioned to try to impregnate - or at least have sex with - as many females as possible. Centuries ago, that behaviour was supposed to be good for keeping the human race going, because it meant that a lot of women got pregnant. But nowadays, that is not such a good idea!

In the future, try to bear in mind that most young guys, though not all, are very strongly driven by the hormone testosterone and will do the most extraordinary things to get a girl to give in. As you have discovered, that often includes saying 'I love you' or 'I will marry you' in order to persuade a woman to take her clothes off.

Furthermore, under the influence of testosterone, many teenage males will flit from woman to woman like a bee moving from flower to flower.

Finally, I am concerned that you have got quite a habit of being hoodwinked by seducers. I really think that for the next few years you should try real hard not to 'fall in love'! If you do become amorous about somebody, please remember that there is no law that says you must have sex with them.

I thought that most girls had no body hair. But last week for the first time ever, a girl let me 'take liberties' with her. To my amazement she had quite an amount of pubic hair. Is this normal?

A. Yes, it is normal. A lot of today's young guys have seen blue movies or porn magazines in which the girls have shaved their pubic hair. Sometimes the hair has been airbrushed. Either way, these poor young men think that it is normal for a woman to have little pubic hair, or maybe none at all.

That is quite wrong. The average woman has at least as much pubic hair as the average guy. Generally, it forms a sort of rough triangle shape and very often it extends a little, out to the sides and up towards the navel.

A. No, this is known as condom collapse and it is caused from nervousness about using the condom. The best way to remedy this is to get your fiancee to put the condom on you. When a guy feels female fingers doing this for him, it usually makes him remain erect.

A. Hormone replacement therapy is only of use when women have passed through menopause or are near it. That is most unlikely to be the case at your young age, though very occasionally a woman reaches premature menopause at 30-ish. The best thing you could do now is to find yourself a sympathetic counsellor or therapist in the Mandeville area and talk over your sex life with her.

A. No, there is no way that he could possibly detect this. Even a gynaecologist could not deduce that you once fooled around with another woman.

Email questions about medical issues to Doc at saturdaylife@gleanerjm.com.