No. Since in most cases homosexuality is discerned or discovered, and not freely chosen, the Catholic Church teaches that it is not automatically a sin. The Church is fairly accepting toward homosexual persons who discover their desires and inclinations toward same-sex sexual activity.
Yet the Church has consistently taught that to act on these inclinations by engaging in homosexual genital acts is always morally wrong. Why so? Here the Church attempts to be true to the core premises of our Catholic sexual-ethics tradition, while at the same time fostering basic human respect, justice and pastoral care toward gay and lesbian persons. There's no quick answer here. We encourage you to follow the link below to a more complete article on Catholic teaching regarding homosexuality.