There are three things to consider here.
First, let's look at where that "10%" figure comes from. The man who proposed that statistic was named Alfred Kinsey. Back in the 1940's, when he did his "research," the general population wasn't very open to divulging their sexual lives. So he looked elsewhere to find his data.
He arrived at the 10% number by sampling 5300 white male subjects. Of these, 2800 of them were sex offenders or other criminals. He also sought out male prostitutes, and homosexual activists at gay bars. From this bunch, he came to the conclusion that ten percent of all guys are homosexual. Needless to say, those who have studied his methodologies aren't convinced with his conclusions.
Secondly, it appears that the actual numbers for homosexuality are far lower than Kinsey proposed. Paul Cameron Wrote a book called The Gay Nineties, and in it he estimates that the national average of men is 3% and for women it is 1.5%. Regardless of what percentage of the population is gay, this does not determine the morality of a person's actions, or the teaching of the Church. For example, if 10% of the population has shoplifted, this would not make the behavior ethical. So, the Church does not look to modern culture to determine her teaching. She looks to divine revelation, as found in Sacred Scripture and Sacred Tradition.
Thirdly, no matter what percentage of the world has same-sex attractions, they must all be treated with dignity, respect, and love, and called to lives of holiness.