What you were describing about homosexual desire is more accurately described as a disposition, or a tendency, or a propensity to lean towards. People who have such disposition but do not act on it are called people with same-sex attraction. It is not a sin,in fact it is not even wrong, for someone to have an inordinate attraction. Same-sex attraction is a disorder, kind of like a sickness or handicap. The person did not choose it.

In a way, depression, which you also mentioned, is the same. Depression is a mental disorder, which limits or if severe even impedes the person from making sound or positive decisions. The person did not choose this condition and is not free to make responsible decisions. He or she cannot be held sinful for actions chosen under severe depression.