One role of the father in any family is to affirm the masculinity of his sons and the femininity of his daughters. The old concept of lesbian's haveing dysfunctional relationships with their mother's has been rejected by qualified counselors. Although sexual abuse is a contributing factor in some lesbian's it is not universal however there is a higher incidence of sexual abuse among lesbian's than gay men.
As to studies, you will attempt to invalidate any studies that supported my view. Gay activists who still maintain Dean Hamer proved the existance of a gay gene refuse to consider the lack of any control group in his research, which is the reason molecular geneticists did not accept Hamer's research.
We will never find a universal reason or cause for a gay orientation and even if we can it is up to each individual to choose to remain gay or seek reparative therapy.
I emphasize the environmental roots since most of the gay men and lesbian women I know who have successfully altered their orientation can identify home and environmental issues that resulted in the developement of their orientation.
As to Sonia's attitude it is not as uncommon as you may think. On Christian message boards the morality of a gay orientation is the focus of any discussions. In real life Christian's who really understand Christ's message and our mandate will focus on preaching Jesus Christ and Him crucified and resurrected for our benefit. In my personal relationships with gay men and my lesbian relatives I don't beat them over the head with the 9 Bible referrences that label homosexuality a sin. This is totally counter-productive and useless since the Bible is spiritually discerned and not a document we are to legislate. Can you imagine the outcry from heterosexual's if we tried to legislate the execution of adulterers per Lev 20:10, especially in view of Jesus' teaching on divorce and remarriage being adultery? We don't have enough prison's, gas chambers, etc. in this nation to incarcerate and execute all ever-straights who have committed adultery.