I agree with the posts above but they answered from a spiritual angle. The question is asked from the social aspect of a religion which must be answered by looking at the what the religion say about it from its social laws.
Just talking with respect to Hinduism in general, it is believed that the cause of homosexuality is due to the KARMA and REBIRTH. It explains it nicely that in your previous birth if you would have a female and now a male or vice versa, may be the feelings persisting from a previous life...explains why people feel they've got the wrong gender. Some men feel like they "should be" women, some women like they should be men.
Rig VEDA says 'Vikruti Evam Prakriti' (perversity/diversity is what nature is all about, or, what seems un-natural is also natural).
Some examples from Hindu scriptures.
1. In Mahabharata, There was a character named Shikhadi, who was in his previous birth a female was born as male. I am not quite sure whether he was born as a female or male. I have come across variant stories. He was probably born as female and brought up as male and when he was married, his wife found out that he was a female like her.. She went through some gender-change routine/surgery/ritual ?? (not sure)
2. Also, lord Krishna, became a female i.e. took the form of Mohini and married the son of Arjuna, Aravan so that he can be sacrificed in the war.
3. also, Arjuna took the vow of eunuchism for 1 year.
3. From Ramayana, It is said that Bhagiratha Maharaja was born of two female parents.
4. BAHUCHARA devi/mata is a goddess connected with transsexuality and eunuchism.
5. There is the concept of Kinnars (celestial beings) in puranas. I am not too sure about this but the homosexuals are called Kinnars as well in Hindi.
6. There are also specific festivals connected to the worship of such gender-variant deities, some of which are famous in India for their crossdressing devotees and homosexual undertones. These festivals include the Aravan Festival of Tamil Nadu, the Ayyappa and Chamaya-Villaku Festivals of Kerala, the Bahucara-mata Festivals of Gujarat and the Yellamma-devi Festivals of Karnataka etc..
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In Mahabharata it is said,
"Those foolish men of evil conduct who engage in all forms of intercourse, taking advantage of improper wombs (viyoni), and forcing themselves upon other men (pumsaka), are born again without their organs as neuters." (Mahabharata 13.145.52)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`
It is clear that Smritis are against it for sure. But they are not Shrutis but part of yuga-dharma that changes from time to time.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Smritis like Manu Smriti is not valid for Kali-Yug and seems corrupted due to various contradictions found in it.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
So, It is inconclusive from my understanding for what Hinduism has decided on Homosexuality.