That's not what it says actually. If you properly translate what it says you get that for a man to lay with another men (= human being) instead of his own, so if he were to commit adultery.
In general what the bible speaks of does in no way imply that homosexuality is abnormal nor does it say it is sinful anywhere. It is the 'modern' interpretation of it that makes that claim. If you translate what is written to the time it was written in it has a completely different meaning. In the time the Bible was written it was quite normal for humans to have sexual relations of the same sex. It was also normal for older men to marry and have sex with girls around 12-13. Does that mean that people in those days were paedophiles?
1) True enough -- there are many scholars who are looking at the translation from the aspect of the patriarchal society: to treat a man as you would treat a woman, to put him under you and dehumanize him so as to play the proverbial incubus -- that was the issue. Women were property, and to treat a fellow man like property was the abomination.
2) It was fairly common for 12 - 13 year old girls to be having sex and be married really only a couple hundred years ago. They weren't going to school, they weren't being taught to read or run a business or learn a trade. They were there to bear children. "Old enough to bleed", and such.
Which brings me to
3) Pretty much all of this is set up by random ebb and flow of societal norms, many of which in this country were set up by puritanical ######. The Catholic Church actually has written down rights of same sex marriages that were performed in Europe as late as the 14th Century. Polygamy, which is given the ol' okay in the Bible was made illegal in the US because it is "something only the savages do".
Basically, ###### the Puritans, who wouldn't even celebrate Christmas.