In Buddhism, the only "Sin' that refers to your question is "Attachment to sexual pleasure" , which refers to excess and acquiring it by by force, influence, power, betray of trust, deceit, etc.. As far as I know, homoseuality is not part part of the "Sin" unless you acquire it by the method/s enumerated above.
TRANSGRESSION;
3 SINS of the body;
1. Murder, 2. Theft, 3. Adultery.
4 SINS of Speech. 1. Lying. 2. Slander. 3. Abuse,
4. Idle Talk.
3 SINS of the Mind; 1.Covetousness, 2. Hatred, 3.Ignorance..
3 KINDS OF CRAVING
1. Attachment to sensual pleasures,
2. Attachment to existence,
3. Attachment to non-existence..