The buddha didnt say that one sexuality is wrong and another is right. If it is homosexuality or hetrosexuality it doesnt matter, whichever it is it needs to be left behind if one wants to reach nibbana.
One of the precepts for lay people is "to refrain from sexual misconduct". This is a broad term which covers acts such as rape, pedophillia etc. If the sexual activity between lay people is based on mutual love then be it between same sex or opposite sex it cant be unwholesome.
However you will find that some of the pre-exisiting notions of certain cultures have crept in so there will be some thervadains in certain cultures who view homosexuality as sexual misconduct, others see it as a result of past kamma. However as i said this comes from pre-buddhist notions.
As a homosexual myself i never see any notion that the buddha condemed it itself, he just taught that any sexual passion in any form will lead to suffering and so should be abandoned.
Hope this was helpful