Instead of using a Styrofoam cup, a Dutch sperm donor has chosen to make his contributions the natural way.

Ed Houben of Maastricht, the Netherlands, says he's co-produced 87 children – with five on the way – by having sex with their moms, ABC News reports.

The 42-year-old historian says he was practically celibate when he became a sperm donor a decade ago. But he adds that his unconventional sex life is for a good cause.

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Statistically, "natural insemination is faster," says Mr. Houben, who started offering his services on the Internet after exceeding the legal limit for donations at a sperm bank.

Mr. Houben confesses he's not attracted to all the women he serves.

"This isn't Heidi Klum coming round and saying: 'Let's do it,' " he says. "I have a good old-fashioned Catholic guilt feeling and I would be a candidate for therapy if I did this for the wrong reasons."

Aspiring mothers have come to him from Australia, Israel, Britain, Germany, Italy, Luxembourg and Belgium as well as his own country, Mr. Houben says. Occasionally, he'll make a house call if a woman is in her fertility window and unable to travel.

Mr. Houben notes that his services are free of charge, but he is discerning about his clients. All must provide medical records showing they are free of disease and drugs. And he may refuse to impregnate women who smoke, drink or are obese.

The benevolent lothario says he has a 100 million sperm count with "above average quality" and claims an 80-per-cent success rate in helping to produce a child.

Mr. Houben says his girlfriend is fine with what he does in his spare time – they met when she came to him from Spain as a client.

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His mission is to reduce the stigma surrounding sperm donations, which have declined dramatically since the Netherlands banned anonymous sperm donations in 2004, he says.

Mr. Houben maintains that children have a right to know where they come from – a position he upholds by hosting an annual reunion for his offspring.

"So far, I've seen happy people and happy children. If you saw them, you wouldn't question what I'm doing," he says.

Do you see anything wrong with sex being part of sperm donation?