GAYS are not second-class citizens but a gay man certainly makes a second-class mother.

Two lesbian women may be model citizens, but neither of them can be a dad to a little boy.

The most serious objection to gay marriage is that it means gay parenting, and gay parenting means depriving a child of either his mother or his father.

The gay marriage debate, at its heart, is not about the rights and needs of the adults, but of the child.

There are already tragic situations where a child is deprived of a mother or a father - such as the death or desertion of a parent.

Some broken families reform as a homosexual household and nothing can or should be done about that, but such tragedy and brokenness should not be wilfully inflicted on a child by the law of the land.

A child needs at least the chance of a mum and a dad in his or her life and same-sex marriage makes that impossible.

The violation of this fundamental right and profound emotional need of a child means - from the child's perspective - that gay marriage is deprivation, not liberation.

Marriage is a compound right and includes the legal right to children. The normalising of same-sex marriage would mean that gay couples would have equal standing with male-female couples for adopting children.

The "marriage" of two women would deprive an adopted boy of his role model for being a man, and the "marriage" of two men would deprive a growing girl of a mother to learn from and confide in.

The sentimental claptrap that passes for debate on gay marriage would have disgusted even that old atheist philosopher, Bertrand Russell.

Russell understood that society has no interest in passing laws about people's private affairs and that the primary reason for the public contract of marriage is to bind the man to the woman for the long task of rearing their children.

As he wrote in Marriage and Morals: "It is through children alone that sexual relations become of importance to society, and worthy to be taken cognisance of by a legal institution."

Homosexual relations do not give rise to children, so such relations are of no institutional importance to society.

The biological triple-bond of man and woman and child is nature's foundation for human life, not a social fad to be cut to shape according to political whim.

It is beyond the power of any parliament to repeal nature and equate same-sex relationships with the inherently male-female project of family formation.

Yet inner-city Greens and muddled MPs are so out of touch with nature that they think that abolishing a mother will be of no consequence.

They are wrong and any such legislation would be moral vandalism. They are also going against common sense, with 86 per cent of Australians, according to a 2009 Galaxy poll, affirming that children should be raised by their own mother and father.

Opposition to gay marriage is all about the child, and no parliament has the right to impose a motherless or fatherless life on a little child.

Dr David van Gend is a Toowoomba GP and a committee member of the Family Council of Queensland

Originally published as Same-sex marriage hurts kids