The following wording is tricky:
Church people, he [Fr. (Don) Michele de Paolis] said, “completely ignore the phenomenon of homosexuality, which science has now clarified unequivocally: the homosexual orientation is not chosen freely by the person. The boy or girl will discover that it is an approach deeply rooted in personality, which is an essential aspect of his identity: it is not a disease, it is not a perversion.”
Homosexuality (same-sex attraction) is often not chosen, per se. It is often, however, unwanted. More importantly concerning the priest's statement, it is often the result of environment (often abuse and/or neglect of one form or another) after birth and very rarely, if ever, a result of genetics. Epigenetics is even more up in the air but regardless, is susceptible to behavioral influences.
What constitutes a disease is a relative opinion of opposing views. In my view (which I claim is God's view), homosexuality's impact upon individuals and society is decidedly negative. I am confident that time will bear this out.
As for Pope Francis' behavior and statements regarding homosexuality, he is gravely mistaken.