God created them, male and female.

After the fall.
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It cannot be said God created a person to be homosexual - in other words, God did not make you gay.  The natural sexual identity of the human person is male or female.
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The genesis of homosexuality is mysterious and difficult to understand, nevertheless it cannot be said God created the homosexual.  Natural law and scripture defy such an assertion.  As the Catechism teaches: "Basing itself on sacred Scripture, which presents homosexual acts as acts of grave depravity, tradition has always declared that homosexual acts are intrinsically disordered. They are contrary to the natural law. They close the sexual act to the gift of life. They do not proceed from a genuine affective and sexual complementarity. Under no circumstances can they be approved" - Catechism of the Catholic Church 2357
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Even if it could be proven there was a genetic predisposition to homosexuality, it would not make the behavior natural.  A person may be genetically inclined to alcoholism, but it doesn't change the disordered nature of the behavior - it doesn't make alcoholism good. 
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Statements from the Congregation for the Doctrine of the Faith.
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Providing a basic plan for understanding this entire discussion of homosexuality is the theology of creation we find in Genesis. God, in his infinite wisdom and love, brings into existence all of reality as a reflection of his goodness. He fashions mankind, male and female, in his own image and likeness. Human beings, therefore, are nothing less than the work of God himself; and in the complementarity of the sexes, they are called to reflect the inner unity of the Creator. They do this in a striking way in their cooperation with him in the transmission of life by a mutual donation of the self to the other.
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In Genesis 3, we find that this truth about persons being an image of God has been obscured by original sin. There inevitably follows a loss of awareness of the covenantal character of the union these persons had with God and with each other. The human body retains its "spousal significance" but this is now clouded by sin. Thus, in Genesis 19:1-11, the deterioration due to sin continues in the story of the men of Sodom. There can be no doubt of the moral judgement made there against homosexual relations. In Leviticus 18:22 and 20:13, in the course of describing the conditions necessary for belonging to the Chosen People, the author excludes from the People of God those who behave in a homosexual fashion. - On the Pastoral Care of Homosexual Persons

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The 1975 Statement.
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At the present time there are those who, basing themselves on observations in the psychological order, have begun to judge indulgently, and even to excuse completely, homosexual relations between certain people. This they do in opposition to the constant teaching of the Magisterium and to the moral sense of the Christian people.
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A distinction is drawn, and it seems with some reason, between homosexuals whose tendency comes from a false education, from a lack of normal sexual development, from habit, from bad example, or from other similar causes, and is transitory or at least not incurable; and homosexuals who are definitively such because of some kind of innate instinct or a pathological constitution judged to be incurable.
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In regard to this second category of subjects, some people conclude that their tendency is so natural that it justifies in their case homosexual relations within a sincere communion of life and love analogous to marriage, in so far as such homosexuals feel incapable of enduring a solitary life.

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According to the objective moral order, homosexual relations are acts which lack an essential and indispensable finality. In Sacred Scripture they are condemned as a serious depravity and even presented as the sad consequence of rejecting God.[18] This judgment of Scripture does not of course permit us to conclude that all those who suffer from this anomaly are personally responsible for it, but it does attest to the fact that homosexual acts are intrinsically disordered and can in no case be approved of. - DECLARATION ON CERTAIN QUESTIONS CONCERNING SEXUAL ETHICS, 1975
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Art: Michelangelo, Sistine Chapel.  "Noah began to be a man of the soil, and he planted a vineyard. He drank of the wine and became drunk and lay uncovered in his tent. And Ham, the father of Canaan, saw the nakedness of his father and told his two brothers outside." (Genesis 9:20-22)